Eevee: Add Irradiance Grid support

Early implementation. Slow and still has quality
3 ways of storing irradiance:
- Spherical Harmonics: Have problem with directionnal lighting.
- HL2 diffuse cube: Very low resolution but smooth transitions.
- Diffuse cube: High storage requirement.

Also include some name change.

13 files changed, 786 insertions, 236 deletions

diff --git a/source/blender/draw/CMakeLists.txt b/source/blender/draw/CMakeLists.txt
index 35df504fa58..48d502eb342 100644
--- a/source/blender/draw/CMakeLists.txt
+++ b/source/blender/draw/CMakeLists.txt
@@ -118,8 +118,8 @@ data_to_c_simple(engines/clay/shaders/ssao_groundtruth.glsl SRC)
 data_to_c_simple(engines/eevee/shaders/default_frag.glsl SRC)
 data_to_c_simple(engines/eevee/shaders/default_world_frag.glsl SRC)
 data_to_c_simple(engines/eevee/shaders/background_vert.glsl SRC)
-data_to_c_simple(engines/eevee/shaders/lightprobe_filter_frag.glsl SRC)
-data_to_c_simple(engines/eevee/shaders/lightprobe_sh_frag.glsl SRC)
+data_to_c_simple(engines/eevee/shaders/lightprobe_filter_glossy_frag.glsl SRC)
+data_to_c_simple(engines/eevee/shaders/lightprobe_filter_diffuse_frag.glsl SRC)
 data_to_c_simple(engines/eevee/shaders/lightprobe_geom.glsl SRC)
 data_to_c_simple(engines/eevee/shaders/lightprobe_vert.glsl SRC)
 data_to_c_simple(engines/eevee/shaders/lit_surface_frag.glsl SRC)
diff --git a/source/blender/draw/engines/eevee/eevee_data.c b/source/blender/draw/engines/eevee/eevee_data.c
index 52dc35b4977..5639250a076 100644
--- a/source/blender/draw/engines/eevee/eevee_data.c
+++ b/source/blender/draw/engines/eevee/eevee_data.c
@@ -53,13 +53,13 @@ static void eevee_scene_layer_data_free(void *storage)
 	/* Probes */
 	MEM_SAFE_FREE(sldata->probes);
 	DRW_UBO_FREE_SAFE(sldata->probe_ubo);
+	DRW_UBO_FREE_SAFE(sldata->grid_ubo);
 	DRW_FRAMEBUFFER_FREE_SAFE(sldata->probe_fb);
 	DRW_FRAMEBUFFER_FREE_SAFE(sldata->probe_filter_fb);
-	DRW_FRAMEBUFFER_FREE_SAFE(sldata->probe_sh_fb);
 	DRW_TEXTURE_FREE_SAFE(sldata->probe_rt);
 	DRW_TEXTURE_FREE_SAFE(sldata->probe_depth_rt);
 	DRW_TEXTURE_FREE_SAFE(sldata->probe_pool);
-	DRW_TEXTURE_FREE_SAFE(sldata->probe_sh);
+	DRW_TEXTURE_FREE_SAFE(sldata->irradiance_pool);
 }
 
 static void eevee_lamp_data_free(void *storage)
diff --git a/source/blender/draw/engines/eevee/eevee_lightprobes.c b/source/blender/draw/engines/eevee/eevee_lightprobes.c
index 1acdd50635e..53cd49abf78 100644
--- a/source/blender/draw/engines/eevee/eevee_lightprobes.c
+++ b/source/blender/draw/engines/eevee/eevee_lightprobes.c
@@ -47,13 +47,14 @@
 #include "eevee_private.h"
 
 /* TODO Option */
-#define LIGHTPROBE_TYPE_CUBE_SIZE 512
-#define PROBE_SIZE 1024
+#define PROBE_RT_SIZE 512 /* Cube render target */
+#define PROBE_OCTAHEDRON_SIZE 1024
+#define IRRADIANCE_POOL_SIZE 1024
 
 static struct {
 	struct GPUShader *probe_default_sh;
-	struct GPUShader *probe_filter_sh;
-	struct GPUShader *probe_spherical_harmonic_sh;
+	struct GPUShader *probe_filter_glossy_sh;
+	struct GPUShader *probe_filter_diffuse_sh;
 
 	struct GPUTexture *hammersley;
 
@@ -62,8 +63,9 @@ static struct {
 } e_data = {NULL}; /* Engine data */
 
 extern char datatoc_default_world_frag_glsl[];
-extern char datatoc_lightprobe_filter_frag_glsl[];
-extern char datatoc_lightprobe_sh_frag_glsl[];
+extern char datatoc_fullscreen_vert_glsl[];
+extern char datatoc_lightprobe_filter_glossy_frag_glsl[];
+extern char datatoc_lightprobe_filter_diffuse_frag_glsl[];
 extern char datatoc_lightprobe_geom_glsl[];
 extern char datatoc_lightprobe_vert_glsl[];
 extern char datatoc_bsdf_common_lib_glsl[];
@@ -104,17 +106,18 @@ static struct GPUTexture *create_hammersley_sample_texture(int samples)
 
 void EEVEE_lightprobes_init(EEVEE_SceneLayerData *sldata)
 {
-	if (!e_data.probe_filter_sh) {
+	/* Shaders */
+	if (!e_data.probe_filter_glossy_sh) {
 		char *shader_str = NULL;
 
 		DynStr *ds_frag = BLI_dynstr_new();
 		BLI_dynstr_append(ds_frag, datatoc_bsdf_common_lib_glsl);
 		BLI_dynstr_append(ds_frag, datatoc_bsdf_sampling_lib_glsl);
-		BLI_dynstr_append(ds_frag, datatoc_lightprobe_filter_frag_glsl);
+		BLI_dynstr_append(ds_frag, datatoc_lightprobe_filter_glossy_frag_glsl);
 		shader_str = BLI_dynstr_get_cstring(ds_frag);
 		BLI_dynstr_free(ds_frag);
 
-		e_data.probe_filter_sh = DRW_shader_create(
+		e_data.probe_filter_glossy_sh = DRW_shader_create(
 		        datatoc_lightprobe_vert_glsl, datatoc_lightprobe_geom_glsl, shader_str,
 		        "#define HAMMERSLEY_SIZE 1024\n"
 		        "#define NOISE_SIZE 64\n");
@@ -123,34 +126,47 @@ void EEVEE_lightprobes_init(EEVEE_SceneLayerData *sldata)
 		        datatoc_lightprobe_vert_glsl, datatoc_lightprobe_geom_glsl, datatoc_default_world_frag_glsl, NULL);
 
 		MEM_freeN(shader_str);
-	}
 
-	/* Shaders */
-	if (!e_data.hammersley) {
+		ds_frag = BLI_dynstr_new();
+		BLI_dynstr_append(ds_frag, datatoc_bsdf_common_lib_glsl);
+		BLI_dynstr_append(ds_frag, datatoc_bsdf_sampling_lib_glsl);
+		BLI_dynstr_append(ds_frag, datatoc_lightprobe_filter_diffuse_frag_glsl);
+		shader_str = BLI_dynstr_get_cstring(ds_frag);
+		BLI_dynstr_free(ds_frag);
+
+		e_data.probe_filter_diffuse_sh = DRW_shader_create_fullscreen(
+		        shader_str,
+#if defined(IRRADIANCE_SH_L2)
+		        "#define IRRADIANCE_SH_L2\n"
+#elif defined(IRRADIANCE_CUBEMAP)
+		        "#define IRRADIANCE_CUBEMAP\n"
+#elif defined(IRRADIANCE_HL2)
+		        "#define IRRADIANCE_HL2\n"
+#endif
+		        "#define HAMMERSLEY_SIZE 1024\n"
+		        "#define NOISE_SIZE 64\n");
+
+		MEM_freeN(shader_str);
+
 		e_data.hammersley = create_hammersley_sample_texture(1024);
-		e_data.probe_spherical_harmonic_sh = DRW_shader_create_fullscreen(datatoc_lightprobe_sh_frag_glsl, NULL);
 	}
 
 	if (!sldata->probes) {
 		sldata->probes = MEM_callocN(sizeof(EEVEE_LightProbesInfo), "EEVEE_LightProbesInfo");
 		sldata->probe_ubo = DRW_uniformbuffer_create(sizeof(EEVEE_LightProbe) * MAX_PROBE, NULL);
+		sldata->grid_ubo = DRW_uniformbuffer_create(sizeof(EEVEE_LightGrid) * MAX_GRID, NULL);
 	}
 
 	/* Setup Render Target Cubemap */
 	if (!sldata->probe_rt) {
-		sldata->probe_rt = DRW_texture_create_cube(LIGHTPROBE_TYPE_CUBE_SIZE, DRW_TEX_RGBA_16, DRW_TEX_FILTER | DRW_TEX_MIPMAP, NULL);
-		sldata->probe_depth_rt = DRW_texture_create_cube(LIGHTPROBE_TYPE_CUBE_SIZE, DRW_TEX_DEPTH_24, DRW_TEX_FILTER, NULL);
+		sldata->probe_rt = DRW_texture_create_cube(PROBE_RT_SIZE, DRW_TEX_RGBA_16, DRW_TEX_FILTER | DRW_TEX_MIPMAP, NULL);
+		sldata->probe_depth_rt = DRW_texture_create_cube(PROBE_RT_SIZE, DRW_TEX_DEPTH_24, DRW_TEX_FILTER, NULL);
 	}
 
 	DRWFboTexture tex_probe[2] = {{&sldata->probe_depth_rt, DRW_TEX_DEPTH_24, DRW_TEX_FILTER},
 	                              {&sldata->probe_rt, DRW_TEX_RGBA_16, DRW_TEX_FILTER | DRW_TEX_MIPMAP}};
 
-	DRW_framebuffer_init(&sldata->probe_fb, &draw_engine_eevee_type, LIGHTPROBE_TYPE_CUBE_SIZE, LIGHTPROBE_TYPE_CUBE_SIZE, tex_probe, 2);
-
-	/* Spherical Harmonic Buffer */
-	DRWFboTexture tex_sh = {&sldata->probe_sh, DRW_TEX_RGBA_16, DRW_TEX_FILTER | DRW_TEX_MIPMAP};
-
-	DRW_framebuffer_init(&sldata->probe_sh_fb, &draw_engine_eevee_type, 9, 1, &tex_sh, 1);
+	DRW_framebuffer_init(&sldata->probe_fb, &draw_engine_eevee_type, PROBE_RT_SIZE, PROBE_RT_SIZE, tex_probe, 2);
 }
 
 void EEVEE_lightprobes_cache_init(EEVEE_SceneLayerData *sldata, EEVEE_PassList *psl)
@@ -158,7 +174,9 @@ void EEVEE_lightprobes_cache_init(EEVEE_SceneLayerData *sldata, EEVEE_PassList *
 	EEVEE_LightProbesInfo *pinfo = sldata->probes;
 
 	pinfo->num_cube = 1; /* at least one for the world */
-	memset(pinfo->probes_ref, 0, sizeof(pinfo->probes_ref));
+	pinfo->num_grid = 0;
+	memset(pinfo->probes_cube_ref, 0, sizeof(pinfo->probes_cube_ref));
+	memset(pinfo->probes_grid_ref, 0, sizeof(pinfo->probes_grid_ref));
 
 	{
 		psl->probe_background = DRW_pass_create("World Probe Pass", DRW_STATE_WRITE_COLOR);
@@ -212,11 +230,11 @@ void EEVEE_lightprobes_cache_init(EEVEE_SceneLayerData *sldata, EEVEE_PassList *
 	}
 
 	{
-		psl->probe_prefilter = DRW_pass_create("LightProbe Filtering", DRW_STATE_WRITE_COLOR);
+		psl->probe_glossy_compute = DRW_pass_create("LightProbe Glossy Compute", DRW_STATE_WRITE_COLOR);
 
 		struct Batch *geom = DRW_cache_fullscreen_quad_get();
 
-		DRWShadingGroup *grp = DRW_shgroup_instance_create(e_data.probe_filter_sh, psl->probe_prefilter, geom);
+		DRWShadingGroup *grp = DRW_shgroup_instance_create(e_data.probe_filter_glossy_sh, psl->probe_glossy_compute, geom);
 		DRW_shgroup_uniform_float(grp, "sampleCount", &sldata->probes->samples_ct, 1);
 		DRW_shgroup_uniform_float(grp, "invSampleCount", &sldata->probes->invsamples_ct, 1);
 		DRW_shgroup_uniform_float(grp, "roughnessSquared", &sldata->probes->roughness, 1);
@@ -233,11 +251,17 @@ void EEVEE_lightprobes_cache_init(EEVEE_SceneLayerData *sldata, EEVEE_PassList *
 	}
 
 	{
-		psl->probe_sh_compute = DRW_pass_create("LightProbe SH Compute", DRW_STATE_WRITE_COLOR);
+		psl->probe_diffuse_compute = DRW_pass_create("LightProbe Diffuse Compute", DRW_STATE_WRITE_COLOR);
 
-		DRWShadingGroup *grp = DRW_shgroup_create(e_data.probe_spherical_harmonic_sh, psl->probe_sh_compute);
+		DRWShadingGroup *grp = DRW_shgroup_create(e_data.probe_filter_diffuse_sh, psl->probe_diffuse_compute);
+#ifdef IRRADIANCE_SH_L2
 		DRW_shgroup_uniform_int(grp, "probeSize", &sldata->probes->shres, 1);
-		DRW_shgroup_uniform_float(grp, "lodBias", &sldata->probes->lodfactor, 1);
+#else
+		DRW_shgroup_uniform_float(grp, "sampleCount", &sldata->probes->samples_ct, 1);
+		DRW_shgroup_uniform_float(grp, "invSampleCount", &sldata->probes->invsamples_ct, 1);
+		DRW_shgroup_uniform_float(grp, "lodFactor", &sldata->probes->lodfactor, 1);
+		DRW_shgroup_uniform_float(grp, "lodMax", &sldata->probes->lodmax, 1);
+#endif
 		DRW_shgroup_uniform_texture(grp, "probeHdr", sldata->probe_rt);
 
 		struct Batch *geom = DRW_cache_fullscreen_quad_get();
@@ -248,26 +272,34 @@ void EEVEE_lightprobes_cache_init(EEVEE_SceneLayerData *sldata, EEVEE_PassList *
 void EEVEE_lightprobes_cache_add(EEVEE_SceneLayerData *sldata, Object *ob)
 {
 	EEVEE_LightProbesInfo *pinfo = sldata->probes;
+	LightProbe *probe = (LightProbe *)ob->data;
 
 	/* Step 1 find all lamps in the scene and setup them */
-	if (pinfo->num_cube > MAX_PROBE) {
+	if ((probe->type == LIGHTPROBE_TYPE_CUBE && pinfo->num_cube >= MAX_PROBE) ||
+		(probe->type == LIGHTPROBE_TYPE_GRID && pinfo->num_grid >= MAX_PROBE))
+	{
 		printf("Too much probes in the scene !!!\n");
-		pinfo->num_cube = MAX_PROBE;
+		return;
 	}
-	else {
-		EEVEE_LightProbeEngineData *ped = EEVEE_lightprobe_data_get(ob);
 
-		if ((ob->deg_update_flag & DEG_RUNTIME_DATA_UPDATE) != 0) {
-			ped->need_update = true;
-		}
+	EEVEE_LightProbeEngineData *ped = EEVEE_lightprobe_data_get(ob);
 
-		if (e_data.update_world) {
-			ped->need_update = true;
-		}
+	if ((ob->deg_update_flag & DEG_RUNTIME_DATA_UPDATE) != 0) {
+		ped->need_update = true;
+	}
 
-		pinfo->probes_ref[pinfo->num_cube] = ob;
+	if (e_data.update_world) {
+		ped->need_update = true;
+	}
+
+	if (probe->type == LIGHTPROBE_TYPE_CUBE) {
+		pinfo->probes_cube_ref[pinfo->num_cube] = ob;
 		pinfo->num_cube++;
 	}
+	else { /* GRID */
+		pinfo->probes_grid_ref[pinfo->num_grid] = ob;
+		pinfo->num_grid++;
+	}
 }
 
 static void EEVEE_lightprobes_updates(EEVEE_SceneLayerData *sldata)
@@ -275,10 +307,13 @@ static void EEVEE_lightprobes_updates(EEVEE_SceneLayerData *sldata)
 	EEVEE_LightProbesInfo *pinfo = sldata->probes;
 	Object *ob;
 
-	for (int i = 1; (ob = pinfo->probes_ref[i]) && (i < MAX_PROBE); i++) {
+	for (int i = 1; (ob = pinfo->probes_cube_ref[i]) && (i < MAX_PROBE); i++) {
 		LightProbe *probe = (LightProbe *)ob->data;
 		EEVEE_LightProbe *eprobe = &pinfo->probe_data[i];
 
+		/* Update transforms */
+		copy_v3_v3(eprobe->position, ob->obmat[3]);
+
 		/* Attenuation */
 		eprobe->attenuation_type = probe->attenuation_type;
 		eprobe->attenuation_fac = 1.0f / max_ff(1e-8f, probe->falloff);
@@ -304,6 +339,67 @@ static void EEVEE_lightprobes_updates(EEVEE_SceneLayerData *sldata)
 		mul_m4_m4m4(eprobe->parallaxmat, ob->obmat, eprobe->parallaxmat);
 		invert_m4(eprobe->parallaxmat);
 	}
+
+	int offset = 1; /* to account for the world probe */
+	for (int i = 0; (ob = pinfo->probes_grid_ref[i]) && (i < MAX_GRID); i++) {
+		LightProbe *probe = (LightProbe *)ob->data;
+		EEVEE_LightGrid *egrid = &pinfo->grid_data[i];
+
+		egrid->offset = offset;
+
+		/* Set offset for the next grid */
+		offset += probe->grid_resolution_x * probe->grid_resolution_y * probe->grid_resolution_z;
+
+		/* Update transforms */
+		float tmp[4][4] = {
+			{2.0f, 0.0f, 0.0f, 0.0f},
+			{0.0f, 2.0f, 0.0f, 0.0f},
+			{0.0f, 0.0f, 2.0f, 0.0f},
+			{-1.0f, -1.0f, -1.0f, 1.0f}
+		};
+		float tmp_grid_mat[4][4] = {
+			{1.0f / (float)(probe->grid_resolution_x + 1), 0.0f, 0.0f, 0.0f},
+			{0.0f, 1.0f / (float)(probe->grid_resolution_y + 1), 0.0f, 0.0f},
+			{0.0f, 0.0f, 1.0f / (float)(probe->grid_resolution_z + 1), 0.0f},
+			{0.0f, 0.0f, 0.0f, 1.0f}
+		};
+		mul_m4_m4m4(tmp, tmp, tmp_grid_mat);
+		mul_m4_m4m4(egrid->mat, ob->obmat, tmp);
+		invert_m4(egrid->mat);
+
+		float one_div_res[3];
+		one_div_res[0] = 2.0f / (float)(probe->grid_resolution_x + 1);
+		one_div_res[1] = 2.0f / (float)(probe->grid_resolution_y + 1);
+		one_div_res[2] = 2.0f / (float)(probe->grid_resolution_z + 1);
+
+		/* First cell. */
+		copy_v3_v3(egrid->corner, one_div_res);
+		add_v3_fl(egrid->corner, -1.0f);
+		mul_m4_v3(ob->obmat, egrid->corner);
+
+		/* Opposite neighbor cell. */
+		copy_v3_fl3(egrid->increment_x, one_div_res[0], 0.0f, 0.0f);
+		add_v3_v3(egrid->increment_x, one_div_res);
+		add_v3_fl(egrid->increment_x, -1.0f);
+		mul_m4_v3(ob->obmat, egrid->increment_x);
+		sub_v3_v3(egrid->increment_x, egrid->corner);
+
+		copy_v3_fl3(egrid->increment_y, 0.0f, one_div_res[1], 0.0f);
+		add_v3_v3(egrid->increment_y, one_div_res);
+		add_v3_fl(egrid->increment_y, -1.0f);
+		mul_m4_v3(ob->obmat, egrid->increment_y);
+		sub_v3_v3(egrid->increment_y, egrid->corner);
+
+		copy_v3_fl3(egrid->increment_z, 0.0f, 0.0f, one_div_res[2]);
+		add_v3_v3(egrid->increment_z, one_div_res);
+		add_v3_fl(egrid->increment_z, -1.0f);
+		mul_m4_v3(ob->obmat, egrid->increment_z);
+		sub_v3_v3(egrid->increment_z, egrid->corner);
+
+		copy_v3_v3_int(egrid->resolution, &probe->grid_resolution_x);
+	}
+
+	pinfo->num_render_grid = pinfo->num_grid;
 }
 
 void EEVEE_lightprobes_cache_finish(EEVEE_SceneLayerData *sldata)
@@ -318,7 +414,7 @@ void EEVEE_lightprobes_cache_finish(EEVEE_SceneLayerData *sldata)
 	}
 
 	if (!sldata->probe_pool) {
-		sldata->probe_pool = DRW_texture_create_2D_array(PROBE_SIZE, PROBE_SIZE, max_ff(1, pinfo->num_cube),
+		sldata->probe_pool = DRW_texture_create_2D_array(PROBE_OCTAHEDRON_SIZE, PROBE_OCTAHEDRON_SIZE, max_ff(1, pinfo->num_cube),
 		                                                 DRW_TEX_RGB_11_11_10, DRW_TEX_FILTER | DRW_TEX_MIPMAP, NULL);
 		if (sldata->probe_filter_fb) {
 			DRW_framebuffer_texture_attach(sldata->probe_filter_fb, sldata->probe_pool, 0, 0);
@@ -327,27 +423,35 @@ void EEVEE_lightprobes_cache_finish(EEVEE_SceneLayerData *sldata)
 		/* Tag probes to refresh */
 		e_data.update_world = true;
 		e_data.world_ready_to_shade = false;
-		pinfo->num_render_probe = 0;
+		pinfo->num_render_cube = 0;
 		pinfo->update_flag |= PROBE_UPDATE_CUBE;
 		pinfo->cache_num_cube = pinfo->num_cube;
 
-		for (int i = 1; (ob = pinfo->probes_ref[i]) && (i < MAX_PROBE); i++) {
+		for (int i = 1; (ob = pinfo->probes_cube_ref[i]) && (i < MAX_PROBE); i++) {
 			EEVEE_LightProbeEngineData *ped = EEVEE_lightprobe_data_get(ob);
 			ped->need_update = true;
 			ped->ready_to_shade = false;
 		}
 	}
 
-	DRWFboTexture tex_filter = {&sldata->probe_pool, DRW_TEX_RGB_11_11_10, DRW_TEX_FILTER | DRW_TEX_MIPMAP};
+	DRWFboTexture tex_filter = {&sldata->probe_pool, DRW_TEX_RGBA_16, DRW_TEX_FILTER | DRW_TEX_MIPMAP};
 
-	DRW_framebuffer_init(&sldata->probe_filter_fb, &draw_engine_eevee_type, PROBE_SIZE, PROBE_SIZE, &tex_filter, 1);
+	DRW_framebuffer_init(&sldata->probe_filter_fb, &draw_engine_eevee_type, PROBE_OCTAHEDRON_SIZE, PROBE_OCTAHEDRON_SIZE, &tex_filter, 1);
+
+	/* TODO Allocate bigger storage if needed. */
+	if (!sldata->irradiance_pool) {
+		sldata->irradiance_pool = DRW_texture_create_2D(IRRADIANCE_POOL_SIZE, IRRADIANCE_POOL_SIZE, DRW_TEX_RGBA_16, DRW_TEX_FILTER, NULL);
+		pinfo->num_render_grid = 0;
+	}
 
 	EEVEE_lightprobes_updates(sldata);
 
 	DRW_uniformbuffer_update(sldata->probe_ubo, &sldata->probes->probe_data);
+	DRW_uniformbuffer_update(sldata->grid_ubo, &sldata->probes->grid_data);
 }
 
-static void filter_probe(EEVEE_LightProbe *eprobe, EEVEE_SceneLayerData *sldata, EEVEE_PassList *psl, int probe_idx)
+/* Glossy filter probe_rt to probe_pool at index probe_idx */
+static void glossy_filter_probe(EEVEE_SceneLayerData *sldata, EEVEE_PassList *psl, int probe_idx)
 {
 	EEVEE_LightProbesInfo *pinfo = sldata->probes;
 
@@ -359,8 +463,8 @@ static void filter_probe(EEVEE_LightProbe *eprobe, EEVEE_SceneLayerData *sldata,
 	/* 3 - Render to probe array to the specified layer, do prefiltering. */
 	/* Detach to rebind the right mipmap. */
 	DRW_framebuffer_texture_detach(sldata->probe_pool);
-	float mipsize = PROBE_SIZE;
-	const int maxlevel = (int)floorf(log2f(PROBE_SIZE));
+	float mipsize = PROBE_OCTAHEDRON_SIZE;
+	const int maxlevel = (int)floorf(log2f(PROBE_OCTAHEDRON_SIZE));
 	const int min_lod_level = 3;
 	for (int i = 0; i < maxlevel - min_lod_level; i++) {
 		float bias = (i == 0) ? 0.0f : 1.0f;
@@ -399,12 +503,12 @@ static void filter_probe(EEVEE_LightProbe *eprobe, EEVEE_SceneLayerData *sldata,
 #endif
 
 		pinfo->invsamples_ct = 1.0f / pinfo->samples_ct;
-		pinfo->lodfactor = bias + 0.5f * log((float)(LIGHTPROBE_TYPE_CUBE_SIZE * LIGHTPROBE_TYPE_CUBE_SIZE) * pinfo->invsamples_ct) / log(2);
-		pinfo->lodmax = floorf(log2f(LIGHTPROBE_TYPE_CUBE_SIZE)) - 2.0f;
+		pinfo->lodfactor = bias + 0.5f * log((float)(PROBE_RT_SIZE * PROBE_RT_SIZE) * pinfo->invsamples_ct) / log(2);
+		pinfo->lodmax = floorf(log2f(PROBE_RT_SIZE)) - 2.0f;
 
 		DRW_framebuffer_texture_attach(sldata->probe_filter_fb, sldata->probe_pool, 0, i);
-		DRW_framebuffer_viewport_size(sldata->probe_filter_fb, mipsize, mipsize);
-		DRW_draw_pass(psl->probe_prefilter);
+		DRW_framebuffer_viewport_size(sldata->probe_filter_fb, 0, 0, mipsize, mipsize);
+		DRW_draw_pass(psl->probe_glossy_compute);
 		DRW_framebuffer_texture_detach(sldata->probe_pool);
 
 		mipsize /= 2;
@@ -413,42 +517,83 @@ static void filter_probe(EEVEE_LightProbe *eprobe, EEVEE_SceneLayerData *sldata,
 	/* For shading, save max level of the octahedron map */
 	pinfo->lodmax = (float)(maxlevel - min_lod_level) - 1.0f;
 
+	/* reattach to have a valid framebuffer. */
+	DRW_framebuffer_texture_attach(sldata->probe_filter_fb, sldata->probe_pool, 0, 0);
+}
+
+/* Diffuse filter probe_rt to irradiance_pool at index probe_idx */
+static void diffuse_filter_probe(EEVEE_SceneLayerData *sldata, EEVEE_PassList *psl, int cell_idx)
+{
+	EEVEE_LightProbesInfo *pinfo = sldata->probes;
+
+	/* TODO do things properly */
+	float lodmax = pinfo->lodmax;
+
 	/* 4 - Compute spherical harmonics */
 	/* Tweaking parameters to balance perf. vs precision */
-	pinfo->shres = 16; /* Less texture fetches & reduce branches */
-	pinfo->lodfactor = 4.0f; /* Improve cache reuse */
-	DRW_framebuffer_bind(sldata->probe_sh_fb);
-	DRW_draw_pass(psl->probe_sh_compute);
-	DRW_framebuffer_read_data(0, 0, 9, 1, 3, 0, (float *)eprobe->shcoefs);
+	DRW_framebuffer_bind(sldata->probe_filter_fb);
+	DRW_texture_generate_mipmaps(sldata->probe_rt);
+
+	/* Bind the right texture layer (one layer per irradiance grid) */
+	DRW_framebuffer_texture_detach(sldata->probe_pool);
+	DRW_framebuffer_texture_attach(sldata->probe_filter_fb, sldata->irradiance_pool, 0, 0);
+
+	/* find cell position on the virtual 3D texture */
+	/* NOTE : Keep in sync with load_irradiance_cell() */
+#if defined(IRRADIANCE_SH_L2)
+	int size[2] = {3, 3};
+#elif defined(IRRADIANCE_CUBEMAP)
+	int size[2] = {8, 8};
+	pinfo->samples_ct = 1024.0f;
+#elif defined(IRRADIANCE_HL2)
+	int size[2] = {3, 2};
+	pinfo->samples_ct = 1024.0f;
+#endif
+
+	int cell_per_row = IRRADIANCE_POOL_SIZE / size[0];
+	int x = size[0] * (cell_idx % cell_per_row);
+	int y = size[1] * (cell_idx / cell_per_row);
+
+#ifndef IRRADIANCE_SH_L2
+	const float bias = 0.0f;
+	pinfo->invsamples_ct = 1.0f / pinfo->samples_ct;
+	pinfo->lodfactor = bias + 0.5f * log((float)(PROBE_RT_SIZE * PROBE_RT_SIZE) * pinfo->invsamples_ct) / log(2);
+	pinfo->lodmax = floorf(log2f(PROBE_RT_SIZE)) - 2.0f;
+#else
+	pinfo->shres = 32; /* Less texture fetches & reduce branches */
+	pinfo->lodmax = 2.0f; /* Improve cache reuse */
+#endif
+
+	DRW_framebuffer_viewport_size(sldata->probe_filter_fb, x, y, size[0], size[1]);
+	DRW_draw_pass(psl->probe_diffuse_compute);
 
 	/* reattach to have a valid framebuffer. */
+	DRW_framebuffer_texture_detach(sldata->irradiance_pool);
 	DRW_framebuffer_texture_attach(sldata->probe_filter_fb, sldata->probe_pool, 0, 0);
+
+	/* restore */
+	pinfo->lodmax = lodmax;
 }
 
-/* Renders the probe with index probe_idx.
- * Renders the world probe if probe_idx = -1. */
-static void render_one_probe(EEVEE_SceneLayerData *sldata, EEVEE_PassList *psl, int probe_idx)
+/* Render the scene to the probe_rt texture. */
+static void render_scene_to_probe(
+        EEVEE_SceneLayerData *sldata, EEVEE_PassList *psl,
+        const float pos[3], float clipsta, float clipend)
 {
 	EEVEE_LightProbesInfo *pinfo = sldata->probes;
-	EEVEE_LightProbe *eprobe = &pinfo->probe_data[probe_idx];
-	Object *ob = pinfo->probes_ref[probe_idx];
-	LightProbe *prb = (LightProbe *)ob->data;
 
 	float winmat[4][4], posmat[4][4];
 
 	unit_m4(posmat);
 
-	/* Update transforms */
-	copy_v3_v3(eprobe->position, ob->obmat[3]);
-
 	/* Move to capture position */
-	negate_v3_v3(posmat[3], ob->obmat[3]);
+	negate_v3_v3(posmat[3], pos);
 
 	/* 1 - Render to each cubeface individually.
 	 * We do this instead of using geometry shader because a) it's faster,
 	 * b) it's easier than fixing the nodetree shaders (for view dependant effects). */
 	pinfo->layer = 0;
-	perspective_m4(winmat, -prb->clipsta, prb->clipsta, -prb->clipsta, prb->clipsta, prb->clipsta, prb->clipend);
+	perspective_m4(winmat, -clipsta, clipsta, -clipsta, clipsta, clipsta, clipend);
 
 	/* Detach to rebind the right cubeface. */
 	DRW_framebuffer_bind(sldata->probe_fb);
@@ -460,9 +605,10 @@ static void render_one_probe(EEVEE_SceneLayerData *sldata, EEVEE_PassList *psl,
 
 		DRW_framebuffer_cubeface_attach(sldata->probe_fb, sldata->probe_rt, 0, i, 0);
 		DRW_framebuffer_cubeface_attach(sldata->probe_fb, sldata->probe_depth_rt, 0, i, 0);
-		DRW_framebuffer_viewport_size(sldata->probe_fb, LIGHTPROBE_TYPE_CUBE_SIZE, LIGHTPROBE_TYPE_CUBE_SIZE);
+		DRW_framebuffer_viewport_size(sldata->probe_fb, 0, 0, PROBE_RT_SIZE, PROBE_RT_SIZE);
 
-		DRW_framebuffer_clear(false, true, false, NULL, 1.0);
+		float clear[4] = {1.0f, 0.0f, 0.0f, 1.0f};
+		DRW_framebuffer_clear(true, true, false, clear, 1.0);
 
 		/* Setup custom matrices */
 		mul_m4_m4m4(viewmat, cubefacemat[i], posmat);
@@ -498,14 +644,11 @@ static void render_one_probe(EEVEE_SceneLayerData *sldata, EEVEE_PassList *psl,
 	DRW_viewport_matrix_override_unset(DRW_MAT_VIEW);
 	DRW_viewport_matrix_override_unset(DRW_MAT_VIEWINV);
 	DRW_viewport_matrix_override_unset(DRW_MAT_WIN);
-
-	filter_probe(eprobe, sldata, psl, probe_idx);
 }
 
-static void render_world_lightprobe(EEVEE_SceneLayerData *sldata, EEVEE_PassList *psl)
+static void render_world_to_probe(EEVEE_SceneLayerData *sldata, EEVEE_PassList *psl)
 {
 	EEVEE_LightProbesInfo *pinfo = sldata->probes;
-	EEVEE_LightProbe *eprobe = &pinfo->probe_data[0];
 
 	/* 1 - Render to cubemap target using geometry shader. */
 	/* For world probe, we don't need to clear since we render the background directly. */
@@ -513,8 +656,51 @@ static void render_world_lightprobe(EEVEE_SceneLayerData *sldata, EEVEE_PassList
 
 	DRW_framebuffer_bind(sldata->probe_fb);
 	DRW_draw_pass(psl->probe_background);
+}
+
+static void update_irradiance_probe(EEVEE_SceneLayerData *sldata, EEVEE_PassList *psl, int probe_idx)
+{
+	EEVEE_LightProbesInfo *pinfo = sldata->probes;
+	EEVEE_LightGrid *egrid = &pinfo->grid_data[probe_idx];
+	Object *ob = pinfo->probes_grid_ref[probe_idx];
+	LightProbe *prb = (LightProbe *)ob->data;
+
+	/* Temporary Remove all grids */
+	int tmp_num_render_grid = pinfo->num_render_grid;
+	int tmp_num_render_cube = pinfo->num_render_cube;
+	pinfo->num_render_grid = 0;
+	pinfo->num_render_cube = 0;
+
+	/* Render a cubemap and compute irradiance for every point inside the irradiance grid */
+	for (int i = 0; i < egrid->resolution[0]; ++i)	{
+		for (int j = 0; j < egrid->resolution[1]; ++j)	{
+			for (int k = 0; k < egrid->resolution[2]; ++k)	{
+				float pos[3], tmp[3];
+				int cell = egrid->offset + k + j * egrid->resolution[2] + i * egrid->resolution[2] * egrid->resolution[1];
+
+				/* Compute world position of the sample */
+				copy_v3_v3(pos, egrid->corner);
+				mul_v3_v3fl(tmp, egrid->increment_x, (float)i);
+				add_v3_v3(pos, tmp);
+				mul_v3_v3fl(tmp, egrid->increment_y, (float)j);
+				add_v3_v3(pos, tmp);
+				mul_v3_v3fl(tmp, egrid->increment_z, (float)k);
+				add_v3_v3(pos, tmp);
+
+				/* TODO Remove specular */
+				render_scene_to_probe(sldata, psl, pos, prb->clipsta, prb->clipend);
+				/* TODO Do not update texture while rendering but write to CPU memory (or another buffer).
+				 * This will allow "multiple bounces" computation. */
+				diffuse_filter_probe(sldata, psl, cell);
+			}
+		}
+	}
+
+	/* Restore */
+	pinfo->num_render_grid = tmp_num_render_grid;
+	pinfo->num_render_cube = tmp_num_render_cube;
 
-	filter_probe(eprobe, sldata, psl, 0);
+	/* TODO save in DNA / blendfile */
 }
 
 void EEVEE_lightprobes_refresh(EEVEE_SceneLayerData *sldata, EEVEE_PassList *psl)
@@ -526,16 +712,17 @@ void EEVEE_lightprobes_refresh(EEVEE_SceneLayerData *sldata, EEVEE_PassList *psl
 
 	/* Render world in priority */
 	if (e_data.update_world) {
-		render_world_lightprobe(sldata, psl);
+		render_world_to_probe(sldata, psl);
+		glossy_filter_probe(sldata, psl, 0);
+		diffuse_filter_probe(sldata, psl, 0);
+
 		e_data.update_world = false;
 
 		if (!e_data.world_ready_to_shade) {
 			e_data.world_ready_to_shade = true;
-			pinfo->num_render_probe = 1;
+			pinfo->num_render_cube = 1;
 		}
 
-		DRW_uniformbuffer_update(sldata->probe_ubo, &sldata->probes->probe_data);
-
 		DRW_viewport_request_redraw();
 	}
 	else if (true) { /* TODO if at least one probe needs refresh */
@@ -548,19 +735,41 @@ void EEVEE_lightprobes_refresh(EEVEE_SceneLayerData *sldata, EEVEE_PassList *psl
 			}
 		}
 
-		for (int i = 1; (ob = pinfo->probes_ref[i]) && (i < MAX_PROBE); i++) {
+		for (int i = 1; (ob = pinfo->probes_cube_ref[i]) && (i < MAX_PROBE); i++) {
 			EEVEE_LightProbeEngineData *ped = EEVEE_lightprobe_data_get(ob);
 
 			if (ped->need_update) {
-				render_one_probe(sldata, psl, i);
+				LightProbe *prb = (LightProbe *)ob->data;
+
+				render_scene_to_probe(sldata, psl, ob->obmat[3], prb->clipsta, prb->clipend);
+				glossy_filter_probe(sldata, psl, i);
+
 				ped->need_update = false;
 
 				if (!ped->ready_to_shade) {
-					pinfo->num_render_probe++;
+					pinfo->num_render_cube++;
 					ped->ready_to_shade = true;
 				}
 
-				DRW_uniformbuffer_update(sldata->probe_ubo, &sldata->probes->probe_data);
+				DRW_viewport_request_redraw();
+
+				/* Only do one probe per frame */
+				break;
+			}
+		}
+
+		for (int i = 0; (ob = pinfo->probes_grid_ref[i]) && (i < MAX_GRID); i++) {
+			EEVEE_LightProbeEngineData *ped = EEVEE_lightprobe_data_get(ob);
+
+			if (ped->need_update) {
+				update_irradiance_probe(sldata, psl, i);
+
+				ped->need_update = false;
+
+				if (!ped->ready_to_shade) {
+					pinfo->num_render_grid++;
+					ped->ready_to_shade = true;
+				}
 
 				DRW_viewport_request_redraw();
 
@@ -574,7 +783,7 @@ void EEVEE_lightprobes_refresh(EEVEE_SceneLayerData *sldata, EEVEE_PassList *psl
 void EEVEE_lightprobes_free(void)
 {
 	DRW_SHADER_FREE_SAFE(e_data.probe_default_sh);
-	DRW_SHADER_FREE_SAFE(e_data.probe_filter_sh);
-	DRW_SHADER_FREE_SAFE(e_data.probe_spherical_harmonic_sh);
+	DRW_SHADER_FREE_SAFE(e_data.probe_filter_glossy_sh);
+	DRW_SHADER_FREE_SAFE(e_data.probe_filter_diffuse_sh);
 	DRW_TEXTURE_FREE_SAFE(e_data.hammersley);
 }
diff --git a/source/blender/draw/engines/eevee/eevee_materials.c b/source/blender/draw/engines/eevee/eevee_materials.c
index b9ad507c6ce..40e6a89d209 100644
--- a/source/blender/draw/engines/eevee/eevee_materials.c
+++ b/source/blender/draw/engines/eevee/eevee_materials.c
@@ -41,6 +41,7 @@
 #define SHADER_DEFINES \
 	"#define EEVEE_ENGINE\n" \
 	"#define MAX_PROBE " STRINGIFY(MAX_PROBE) "\n" \
+	"#define MAX_GRID " STRINGIFY(MAX_GRID) "\n" \
 	"#define MAX_LIGHT " STRINGIFY(MAX_LIGHT) "\n" \
 	"#define MAX_SHADOW_CUBE " STRINGIFY(MAX_SHADOW_CUBE) "\n" \
 	"#define MAX_SHADOW_MAP " STRINGIFY(MAX_SHADOW_MAP) "\n" \
@@ -87,8 +88,6 @@ extern char datatoc_lit_surface_vert_glsl[];
 extern char datatoc_shadow_frag_glsl[];
 extern char datatoc_shadow_geom_glsl[];
 extern char datatoc_shadow_vert_glsl[];
-extern char datatoc_lightprobe_filter_frag_glsl[];
-extern char datatoc_lightprobe_sh_frag_glsl[];
 extern char datatoc_lightprobe_geom_glsl[];
 extern char datatoc_lightprobe_vert_glsl[];
 extern char datatoc_background_vert_glsl[];
@@ -186,11 +185,25 @@ void EEVEE_materials_init(void)
 		e_data.default_lit = DRW_shader_create(
 		        datatoc_lit_surface_vert_glsl, NULL, frag_str,
 		        SHADER_DEFINES
+#if defined(IRRADIANCE_SH_L2)
+		        "#define IRRADIANCE_SH_L2\n"
+#elif defined(IRRADIANCE_CUBEMAP)
+		        "#define IRRADIANCE_CUBEMAP\n"
+#elif defined(IRRADIANCE_HL2)
+		        "#define IRRADIANCE_HL2\n"
+#endif
 		        "#define MESH_SHADER\n");
 
 		e_data.default_lit_flat = DRW_shader_create(
 		        datatoc_lit_surface_vert_glsl, NULL, frag_str,
 		        SHADER_DEFINES
+#if defined(IRRADIANCE_SH_L2)
+		        "#define IRRADIANCE_SH_L2\n"
+#elif defined(IRRADIANCE_CUBEMAP)
+		        "#define IRRADIANCE_CUBEMAP\n"
+#elif defined(IRRADIANCE_HL2)
+		        "#define IRRADIANCE_HL2\n"
+#endif
 		        "#define MESH_SHADER\n"
 		        "#define USE_FLAT_NORMAL\n");
 
@@ -250,22 +263,21 @@ struct GPUMaterial *EEVEE_material_world_background_get(struct Scene *scene, Wor
 	    SHADER_DEFINES "#define WORLD_BACKGROUND\n");
 }
 
-struct GPUMaterial *EEVEE_material_mesh_lightprobe_get(struct Scene *scene, Material *ma)
-{
-	return GPU_material_from_nodetree(
-	    scene, ma->nodetree, &ma->gpumaterial, &DRW_engine_viewport_eevee_type,
-	    VAR_MAT_MESH | VAR_MAT_PROBE,
-	    datatoc_lightprobe_vert_glsl, NULL, e_data.frag_shader_lib,
-	    SHADER_DEFINES "#define MESH_SHADER\n" "#define PROBE_CAPTURE\n");
-}
-
 struct GPUMaterial *EEVEE_material_mesh_get(struct Scene *scene, Material *ma)
 {
 	return GPU_material_from_nodetree(
 	    scene, ma->nodetree, &ma->gpumaterial, &DRW_engine_viewport_eevee_type,
 	    VAR_MAT_MESH,
 	    datatoc_lit_surface_vert_glsl, NULL, e_data.frag_shader_lib,
-	    SHADER_DEFINES "#define MESH_SHADER\n");
+	    SHADER_DEFINES
+#if defined(IRRADIANCE_SH_L2)
+	    "#define IRRADIANCE_SH_L2\n"
+#elif defined(IRRADIANCE_CUBEMAP)
+	    "#define IRRADIANCE_CUBEMAP\n"
+#elif defined(IRRADIANCE_HL2)
+	    "#define IRRADIANCE_HL2\n"
+#endif
+	    "#define MESH_SHADER\n");
 }
 
 struct GPUMaterial *EEVEE_material_hair_get(struct Scene *scene, Material *ma)
@@ -280,13 +292,16 @@ struct GPUMaterial *EEVEE_material_hair_get(struct Scene *scene, Material *ma)
 static void add_standard_uniforms(DRWShadingGroup *shgrp, EEVEE_SceneLayerData *sldata)
 {
 	DRW_shgroup_uniform_block(shgrp, "probe_block", sldata->probe_ubo);
+	DRW_shgroup_uniform_block(shgrp, "grid_block", sldata->grid_ubo);
 	DRW_shgroup_uniform_block(shgrp, "light_block", sldata->light_ubo);
 	DRW_shgroup_uniform_block(shgrp, "shadow_block", sldata->shadow_ubo);
 	DRW_shgroup_uniform_int(shgrp, "light_count", &sldata->lamps->num_light, 1);
-	DRW_shgroup_uniform_int(shgrp, "probe_count", &sldata->probes->num_render_probe, 1);
+	DRW_shgroup_uniform_int(shgrp, "probe_count", &sldata->probes->num_render_cube, 1);
+	DRW_shgroup_uniform_int(shgrp, "grid_count", &sldata->probes->num_render_grid, 1);
 	DRW_shgroup_uniform_float(shgrp, "lodMax", &sldata->probes->lodmax, 1);
 	DRW_shgroup_uniform_texture(shgrp, "utilTex", e_data.util_tex);
 	DRW_shgroup_uniform_buffer(shgrp, "probeCubes", &sldata->probe_pool);
+	DRW_shgroup_uniform_buffer(shgrp, "irradianceGrid", &sldata->irradiance_pool);
 	DRW_shgroup_uniform_buffer(shgrp, "shadowCubes", &sldata->shadow_depth_cube_pool);
 	DRW_shgroup_uniform_buffer(shgrp, "shadowCascades", &sldata->shadow_depth_cascade_pool);
 }
diff --git a/source/blender/draw/engines/eevee/eevee_private.h b/source/blender/draw/engines/eevee/eevee_private.h
index f3c8a63a5d7..77aa8d04278 100644
--- a/source/blender/draw/engines/eevee/eevee_private.h
+++ b/source/blender/draw/engines/eevee/eevee_private.h
@@ -32,6 +32,7 @@ extern struct DrawEngineType draw_engine_eevee_type;
 
 /* Minimum UBO is 16384 bytes */
 #define MAX_PROBE 128 /* TODO : find size by dividing UBO max size by probe data size */
+#define MAX_GRID 64 /* TODO : find size by dividing UBO max size by grid data size */
 #define MAX_LIGHT 128 /* TODO : find size by dividing UBO max size by light data size */
 #define MAX_SHADOW_CUBE 42 /* TODO : Make this depends on GL_MAX_ARRAY_TEXTURE_LAYERS */
 #define MAX_SHADOW_MAP 64
@@ -39,6 +40,11 @@ extern struct DrawEngineType draw_engine_eevee_type;
 #define MAX_CASCADE_NUM 4
 #define MAX_BLOOM_STEP 16
 
+/* Only define one of these. */
+// #define IRRADIANCE_SH_L2
+// #define IRRADIANCE_CUBEMAP
+#define IRRADIANCE_HL2
+
 typedef struct EEVEE_PassList {
 	/* Shadows */
 	struct DRWPass *shadow_pass;
@@ -49,8 +55,8 @@ typedef struct EEVEE_PassList {
 	/* Probes */
 	struct DRWPass *probe_background;
 	struct DRWPass *probe_meshes;
-	struct DRWPass *probe_prefilter;
-	struct DRWPass *probe_sh_compute;
+	struct DRWPass *probe_glossy_compute;
+	struct DRWPass *probe_diffuse_compute;
 
 	/* Effects */
 	struct DRWPass *motion_blur;
@@ -169,7 +175,6 @@ enum {
 /* ************ PROBE UBO ************* */
 typedef struct EEVEE_LightProbe {
 	float position[3], parallax_type;
-	float shcoefs[9][3], pad2;
 	float attenuation_fac;
 	float attenuation_type;
 	float pad3[2];
@@ -177,12 +182,23 @@ typedef struct EEVEE_LightProbe {
 	float parallaxmat[4][4];
 } EEVEE_LightProbe;
 
+typedef struct EEVEE_LightGrid {
+	float mat[4][4];
+	int resolution[3], offset;
+	float corner[3], pad1;
+	float increment_x[3], pad2; /* world space vector between 2 opposite cells */
+	float increment_y[3], pad3;
+	float increment_z[3], pad4;
+} EEVEE_LightGrid;
+
 /* ************ PROBE DATA ************* */
 typedef struct EEVEE_LightProbesInfo {
 	int num_cube, cache_num_cube;
+	int num_grid, cache_num_grid;
 	int update_flag;
 	/* Actual number of probes that have datas. */
-	int num_render_probe;
+	int num_render_cube;
+	int num_render_grid;
 	/* For rendering probes */
 	float probemat[6][4][4];
 	int layer;
@@ -198,9 +214,11 @@ typedef struct EEVEE_LightProbesInfo {
 	struct GPUTexture *backgroundtex;
 	/* List of probes in the scene. */
 	/* XXX This is fragile, can get out of sync quickly. */
-	struct Object *probes_ref[MAX_PROBE];
+	struct Object *probes_cube_ref[MAX_PROBE];
+	struct Object *probes_grid_ref[MAX_GRID];
 	/* UBO Storage : data used by UBO */
 	struct EEVEE_LightProbe probe_data[MAX_PROBE];
+	struct EEVEE_LightGrid grid_data[MAX_GRID];
 } EEVEE_LightProbesInfo;
 
 /* EEVEE_LightProbesInfo->update_flag */
@@ -274,15 +292,15 @@ typedef struct EEVEE_SceneLayerData {
 	struct EEVEE_LightProbesInfo *probes;
 
 	struct GPUUniformBuffer *probe_ubo;
+	struct GPUUniformBuffer *grid_ubo;
 
 	struct GPUFrameBuffer *probe_fb;
 	struct GPUFrameBuffer *probe_filter_fb;
-	struct GPUFrameBuffer *probe_sh_fb;
 
 	struct GPUTexture *probe_rt;
 	struct GPUTexture *probe_depth_rt;
 	struct GPUTexture *probe_pool;
-	struct GPUTexture *probe_sh;
+	struct GPUTexture *irradiance_pool;
 
 	struct ListBase probe_queue; /* List of probes to update */
 } EEVEE_SceneLayerData;
diff --git a/source/blender/draw/engines/eevee/shaders/bsdf_common_lib.glsl b/source/blender/draw/engines/eevee/shaders/bsdf_common_lib.glsl
index 4aa97780637..77ff614b2c1 100644
--- a/source/blender/draw/engines/eevee/shaders/bsdf_common_lib.glsl
+++ b/source/blender/draw/engines/eevee/shaders/bsdf_common_lib.glsl
@@ -11,7 +11,6 @@
 
 struct ProbeData {
 	vec4 position_type;
-	vec4 shcoefs[7];
 	vec4 attenuation_fac_type;
 	mat4 influencemat;
 	mat4 parallaxmat;
@@ -25,6 +24,36 @@ struct ProbeData {
 #define p_atten_fac     attenuation_fac_type.x
 #define p_atten_type    attenuation_fac_type.y
 
+struct GridData {
+	mat4 localmat;
+	ivec4 resolution_offset;
+	vec4 ws_corner;      /* world space position */
+	vec4 ws_increment_x; /* world space vector between 2 opposite cells */
+	vec4 ws_increment_y;
+	vec4 ws_increment_z;
+};
+
+#define g_corner        ws_corner.xyz
+#define g_increment_x   ws_increment_x.xyz
+#define g_increment_y   ws_increment_y.xyz
+#define g_increment_z   ws_increment_z.xyz
+#define g_resolution    resolution_offset.xyz
+#define g_offset        resolution_offset.w
+
+#ifdef IRRADIANCE_CUBEMAP
+struct IrradianceData {
+	vec3 color;
+};
+#elif defined(IRRADIANCE_SH_L2)
+struct IrradianceData {
+	vec3 shcoefs[9];
+};
+#else /* defined(IRRADIANCE_HL2) */
+struct IrradianceData {
+	vec3 cubesides[3];
+};
+#endif
+
 /* TODO remove sh once we have irradiance grid */
 #define shcoef0        shcoefs[0].rgb
 #define shcoef1        vec3(shcoefs[0].a, shcoefs[1].rg)
@@ -226,38 +255,62 @@ float buffer_depth(bool is_persp, float z, float zf, float zn)
 #define spherical_harmonics spherical_harmonics_L2
 
 /* http://seblagarde.wordpress.com/2012/01/08/pi-or-not-to-pi-in-game-lighting-equation/ */
-vec3 spherical_harmonics_L1(vec3 N, vec4 shcoefs[3])
+vec3 spherical_harmonics_L1(vec3 N, vec3 shcoefs[4])
 {
 	vec3 sh = vec3(0.0);
 
-	sh += 0.282095 * shcoef0;
+	sh += 0.282095 * shcoefs[0];
 
-	sh += -0.488603 * N.z * shcoef1;
-	sh += 0.488603 * N.y * shcoef2;
-	sh += -0.488603 * N.x * shcoef3;
+	sh += -0.488603 * N.z * shcoefs[1];
+	sh += 0.488603 * N.y * shcoefs[2];
+	sh += -0.488603 * N.x * shcoefs[3];
 
 	return sh;
 }
 
-vec3 spherical_harmonics_L2(vec3 N, vec4 shcoefs[7])
+vec3 spherical_harmonics_L2(vec3 N, vec3 shcoefs[9])
 {
 	vec3 sh = vec3(0.0);
 
-	sh += 0.282095 * shcoef0;
+	sh += 0.282095 * shcoefs[0];
 
-	sh += -0.488603 * N.z * shcoef1;
-	sh += 0.488603 * N.y * shcoef2;
-	sh += -0.488603 * N.x * shcoef3;
+	sh += -0.488603 * N.z * shcoefs[1];
+	sh += 0.488603 * N.y * shcoefs[2];
+	sh += -0.488603 * N.x * shcoefs[3];
 
-	sh += 1.092548 * N.x * N.z * shcoef4;
-	sh += -1.092548 * N.z * N.y * shcoef5;
-	sh += 0.315392 * (3.0 * N.y * N.y - 1.0) * shcoef6;
-	sh += -1.092548 * N.x * N.y * shcoef7;
-	sh += 0.546274 * (N.x * N.x - N.z * N.z) * shcoef8;
+	sh += 1.092548 * N.x * N.z * shcoefs[4];
+	sh += -1.092548 * N.z * N.y * shcoefs[5];
+	sh += 0.315392 * (3.0 * N.y * N.y - 1.0) * shcoefs[6];
+	sh += -1.092548 * N.x * N.y * shcoefs[7];
+	sh += 0.546274 * (N.x * N.x - N.z * N.z) * shcoefs[8];
 
 	return sh;
 }
 
+vec3 hl2_basis(vec3 N, vec3 cubesides[3])
+{
+	vec3 irradiance = vec3(0.0);
+
+	vec3 n_squared = N * N;
+
+	irradiance += n_squared.x * cubesides[0];
+	irradiance += n_squared.y * cubesides[1];
+	irradiance += n_squared.z * cubesides[2];
+
+	return irradiance;
+}
+
+vec3 compute_irradiance(vec3 N, IrradianceData ird)
+{
+#if defined(IRRADIANCE_CUBEMAP)
+	return ird.color;
+#elif defined(IRRADIANCE_SH_L2)
+	return spherical_harmonics_L2(N, ird.shcoefs);
+#else /* defined(IRRADIANCE_HL2) */
+	return hl2_basis(N, ird.cubesides);
+#endif
+}
+
 vec3 get_specular_dominant_dir(vec3 N, vec3 R, float roughness)
 {
 	float smoothness = 1.0 - roughness;
diff --git a/source/blender/draw/engines/eevee/shaders/bsdf_sampling_lib.glsl b/source/blender/draw/engines/eevee/shaders/bsdf_sampling_lib.glsl
index 898c7bfc578..3997de7a22d 100644
--- a/source/blender/draw/engines/eevee/shaders/bsdf_sampling_lib.glsl
+++ b/source/blender/draw/engines/eevee/shaders/bsdf_sampling_lib.glsl
@@ -37,6 +37,11 @@ float pdf_ggx_reflect(float NH, float a2)
 	return NH * a2 / D_ggx_opti(NH, a2);
 }
 
+float pdf_hemisphere()
+{
+	return 0.5 * M_1_PI;
+}
+
 vec3 sample_ggx(float nsample, float a2, vec3 N, vec3 T, vec3 B)
 {
 	vec3 Xi = hammersley_3d(nsample);
@@ -52,3 +57,17 @@ vec3 sample_ggx(float nsample, float a2, vec3 N, vec3 T, vec3 B)
 
 	return tangent_to_world(Ht, N, T, B);
 }
+
+vec3 sample_hemisphere(float nsample, vec3 N, vec3 T, vec3 B)
+{
+	vec3 Xi = hammersley_3d(nsample);
+
+	float z = Xi.x; /* cos theta */
+	float r = sqrt( 1.0f - z*z ); /* sin theta */
+	float x = r * Xi.y;
+	float y = r * Xi.z;
+
+	vec3 Ht = vec3(x, y, z);
+
+	return tangent_to_world(Ht, N, T, B);
+}
\ No newline at end of file
diff --git a/source/blender/draw/engines/eevee/shaders/lightprobe_filter_diffuse_frag.glsl b/source/blender/draw/engines/eevee/shaders/lightprobe_filter_diffuse_frag.glsl
new file mode 100644
index 00000000000..c08135aa979
--- /dev/null
+++ b/source/blender/draw/engines/eevee/shaders/lightprobe_filter_diffuse_frag.glsl
@@ -0,0 +1,197 @@
+
+uniform samplerCube probeHdr;
+uniform int probeSize;
+uniform float lodFactor;
+uniform float lodMax;
+
+in vec3 worldPosition;
+
+out vec4 FragColor;
+
+#define M_4PI 12.5663706143591729
+
+const mat3 CUBE_ROTATIONS[6] = mat3[](
+	mat3(vec3( 0.0,  0.0, -1.0),
+		 vec3( 0.0, -1.0,  0.0),
+		 vec3(-1.0,  0.0,  0.0)),
+	mat3(vec3( 0.0,  0.0,  1.0),
+		 vec3( 0.0, -1.0,  0.0),
+		 vec3( 1.0,  0.0,  0.0)),
+	mat3(vec3( 1.0,  0.0,  0.0),
+		 vec3( 0.0,  0.0,  1.0),
+		 vec3( 0.0, -1.0,  0.0)),
+	mat3(vec3( 1.0,  0.0,  0.0),
+		 vec3( 0.0,  0.0, -1.0),
+		 vec3( 0.0,  1.0,  0.0)),
+	mat3(vec3( 1.0,  0.0,  0.0),
+		 vec3( 0.0, -1.0,  0.0),
+		 vec3( 0.0,  0.0, -1.0)),
+	mat3(vec3(-1.0,  0.0,  0.0),
+		 vec3( 0.0, -1.0,  0.0),
+		 vec3( 0.0,  0.0,  1.0)));
+
+vec3 get_cubemap_vector(vec2 co, int face)
+{
+	return normalize(CUBE_ROTATIONS[face] * vec3(co * 2.0 - 1.0, 1.0));
+}
+
+float area_element(float x, float y)
+{
+	return atan(x * y, sqrt(x * x + y * y + 1));
+}
+
+float texel_solid_angle(vec2 co, float halfpix)
+{
+	vec2 v1 = (co - vec2(halfpix)) * 2.0 - 1.0;
+	vec2 v2 = (co + vec2(halfpix)) * 2.0 - 1.0;
+
+	return area_element(v1.x, v1.y) - area_element(v1.x, v2.y) - area_element(v2.x, v1.y) + area_element(v2.x, v2.y);
+}
+
+vec3 octahedral_to_cubemap_proj(vec2 co)
+{
+	co = co * 2.0 - 1.0;
+
+	vec2 abs_co = abs(co);
+	vec3 v = vec3(co, 1.0 - (abs_co.x + abs_co.y));
+
+	if ( abs_co.x + abs_co.y > 1.0 ) {
+		v.xy = (abs(co.yx) - 1.0) * -sign(co.xy);
+	}
+
+	return v;
+}
+
+void main()
+{
+#if defined(IRRADIANCE_SH_L2)
+	float pixstep = 1.0 / probeSize;
+	float halfpix = pixstep / 2.0;
+
+	/* Downside: leaks negative values, very bandwidth consuming */
+	int comp = int(gl_FragCoord.x) % 3 + (int(gl_FragCoord.y) % 3) * 3;
+
+	float weight_accum = 0.0;
+	vec3 sh = vec3(0.0);
+
+	for (int face = 0; face < 6; ++face) {
+		for (float x = halfpix; x < 1.0; x += pixstep) {
+			for (float y = halfpix; y < 1.0; y += pixstep) {
+				float weight, coef;
+				vec2 facecoord = vec2(x,y);
+				vec3 cubevec = get_cubemap_vector(facecoord, face);
+
+				if (comp == 0) {
+					coef = 0.282095;
+				}
+				else if (comp == 1) {
+					coef = -0.488603 * cubevec.z * 2.0 / 3.0;
+				}
+				else if (comp == 2) {
+					coef = 0.488603 * cubevec.y * 2.0 / 3.0;
+				}
+				else if (comp == 3) {
+					coef = -0.488603 * cubevec.x * 2.0 / 3.0;
+				}
+				else if (comp == 4) {
+					coef = 1.092548 * cubevec.x * cubevec.z * 1.0 / 4.0;
+				}
+				else if (comp == 5) {
+					coef = -1.092548 * cubevec.z * cubevec.y * 1.0 / 4.0;
+				}
+				else if (comp == 6) {
+					coef = 0.315392 * (3.0 * cubevec.y * cubevec.y - 1.0) * 1.0 / 4.0;
+				}
+				else if (comp == 7) {
+					coef = 1.092548 * cubevec.x * cubevec.y * 1.0 / 4.0;
+				}
+				else { /* (comp == 8) */
+					coef = 0.546274 * (cubevec.x * cubevec.x - cubevec.z * cubevec.z) * 1.0 / 4.0;
+				}
+
+				weight = texel_solid_angle(facecoord, halfpix);
+
+				vec4 sample = textureLod(probeHdr, cubevec, lodMax);
+				sh += sample.rgb * coef * weight;
+				weight_accum += weight;
+			}
+		}
+	}
+	sh *= M_4PI / weight_accum;
+
+	FragColor = vec4(sh, 1.0);
+#else
+#if defined(IRRADIANCE_CUBEMAP)
+	/* Downside: Need lots of memory for storage, distortion due to octahedral mapping */
+	const vec2 map_size = vec2(16.0);
+	const vec2 texelSize = 1.0 / map_size;
+	vec2 uvs = mod(gl_FragCoord.xy, map_size) * texelSize;
+	const float paddingSize = 1.0;
+
+	/* Add a N pixel border to ensure filtering is correct
+	 * for N mipmap levels. */
+	uvs += uvs * texelSize * paddingSize * 2.0;
+	uvs -= texelSize * paddingSize;
+
+	/* edge mirroring : only mirror if directly adjacent
+	 * (not diagonally adjacent) */
+	vec2 m = abs(uvs - 0.5) + 0.5;
+	vec2 f = floor(m);
+	if (f.x - f.y != 0.0) {
+		uvs = 1.0 - uvs;
+	}
+
+	/* clamp to [0-1] */
+	uvs = fract(uvs);
+
+	/* get cubemap vector */
+	vec3 cubevec = octahedral_to_cubemap_proj(uvs);
+
+#elif defined(IRRADIANCE_HL2)
+	/* Downside: very very low resolution (6 texels), bleed lighting because of interpolation */
+	int x = int(gl_FragCoord.x) % 3;
+	int y = int(gl_FragCoord.y) % 2;
+
+	vec3 cubevec = vec3(1.0, 0.0, 0.0);
+
+	if (x == 1) {
+		cubevec = cubevec.yxy;
+	}
+	else if (x == 2) {
+		cubevec = cubevec.yyx;
+	}
+
+	if (y == 1) {
+		cubevec = -cubevec;
+	}
+#endif
+
+	vec3 N, T, B, V;
+
+	N = normalize(cubevec);
+
+	make_orthonormal_basis(N, T, B); /* Generate tangent space */
+
+	/* Integrating Envmap */
+	float weight = 0.0;
+	vec3 out_radiance = vec3(0.0);
+	for (float i = 0; i < sampleCount; i++) {
+		vec3 L = sample_hemisphere(i, N, T, B); /* Microfacet normal */
+		float NL = dot(N, L);
+
+		if (NL > 0.0) {
+			/* Coarse Approximation of the mapping distortion
+			 * Unit Sphere -> Cubemap Face */
+			const float dist = 4.0 * M_PI / 6.0;
+			float pdf = pdf_hemisphere();
+			/* http://http.developer.nvidia.com/GPUGems3/gpugems3_ch20.html : Equation 13 */
+			float lod = clamp(lodFactor - 0.5 * log2(pdf * dist), 0.0, lodMax) ;
+
+			out_radiance += textureLod(probeHdr, L, lod).rgb * NL / pdf;
+		}
+		weight += 1.0;
+	}
+
+	FragColor = vec4(out_radiance / weight, 1.0);
+#endif
+}
\ No newline at end of file
diff --git a/source/blender/draw/engines/eevee/shaders/lightprobe_filter_frag.glsl b/source/blender/draw/engines/eevee/shaders/lightprobe_filter_glossy_frag.glsl
index 33714c5293c..33714c5293c 100644
--- a/source/blender/draw/engines/eevee/shaders/lightprobe_filter_frag.glsl
+++ b/source/blender/draw/engines/eevee/shaders/lightprobe_filter_glossy_frag.glsl
diff --git a/source/blender/draw/engines/eevee/shaders/lightprobe_sh_frag.glsl b/source/blender/draw/engines/eevee/shaders/lightprobe_sh_frag.glsl
deleted file mode 100644
index 1bb14b76f42..00000000000
--- a/source/blender/draw/engines/eevee/shaders/lightprobe_sh_frag.glsl
+++ /dev/null
@@ -1,107 +0,0 @@
-
-uniform samplerCube probeHdr;
-uniform int probeSize;
-uniform float lodBias;
-
-in vec3 worldPosition;
-
-out vec4 FragColor;
-
-#define M_4PI 12.5663706143591729
-
-const mat3 CUBE_ROTATIONS[6] = mat3[](
-	mat3(vec3( 0.0,  0.0, -1.0),
-		 vec3( 0.0, -1.0,  0.0),
-		 vec3(-1.0,  0.0,  0.0)),
-	mat3(vec3( 0.0,  0.0,  1.0),
-		 vec3( 0.0, -1.0,  0.0),
-		 vec3( 1.0,  0.0,  0.0)),
-	mat3(vec3( 1.0,  0.0,  0.0),
-		 vec3( 0.0,  0.0,  1.0),
-		 vec3( 0.0, -1.0,  0.0)),
-	mat3(vec3( 1.0,  0.0,  0.0),
-		 vec3( 0.0,  0.0, -1.0),
-		 vec3( 0.0,  1.0,  0.0)),
-	mat3(vec3( 1.0,  0.0,  0.0),
-		 vec3( 0.0, -1.0,  0.0),
-		 vec3( 0.0,  0.0, -1.0)),
-	mat3(vec3(-1.0,  0.0,  0.0),
-		 vec3( 0.0, -1.0,  0.0),
-		 vec3( 0.0,  0.0,  1.0)));
-
-vec3 get_cubemap_vector(vec2 co, int face)
-{
-	return normalize(CUBE_ROTATIONS[face] * vec3(co * 2.0 - 1.0, 1.0));
-}
-
-float area_element(float x, float y)
-{
-    return atan(x * y, sqrt(x * x + y * y + 1));
-}
- 
-float texel_solid_angle(vec2 co, float halfpix)
-{
-	vec2 v1 = (co - vec2(halfpix)) * 2.0 - 1.0;
-	vec2 v2 = (co + vec2(halfpix)) * 2.0 - 1.0;
-
-	return area_element(v1.x, v1.y) - area_element(v1.x, v2.y) - area_element(v2.x, v1.y) + area_element(v2.x, v2.y);
-}
-
-void main()
-{
-	float pixstep = 1.0 / probeSize;
-	float halfpix = pixstep / 2.0;
-
-	float weight_accum = 0.0;
-	vec3 sh = vec3(0.0);
-
-	int shnbr = int(floor(gl_FragCoord.x));
-
-	for (int face = 0; face < 6; ++face) {
-		for (float x = halfpix; x < 1.0; x += pixstep) {
-			for (float y = halfpix; y < 1.0; y += pixstep) {
-				float shcoef;
-
-				vec2 facecoord = vec2(x,y);
-				vec3 cubevec = get_cubemap_vector(facecoord, face);
-				float weight = texel_solid_angle(facecoord, halfpix);
-
-				if (shnbr == 0) {
-					shcoef = 0.282095;
-				}
-				else if (shnbr == 1) {
-					shcoef = -0.488603 * cubevec.z * 2.0 / 3.0;
-				}
-				else if (shnbr == 2) {
-					shcoef = 0.488603 * cubevec.y * 2.0 / 3.0;
-				}
-				else if (shnbr == 3) {
-					shcoef = -0.488603 * cubevec.x * 2.0 / 3.0;
-				}
-				else if (shnbr == 4) {
-					shcoef = 1.092548 * cubevec.x * cubevec.z * 1.0 / 4.0;
-				}
-				else if (shnbr == 5) {
-					shcoef = -1.092548 * cubevec.z * cubevec.y * 1.0 / 4.0;
-				}
-				else if (shnbr == 6) {
-					shcoef = 0.315392 * (3.0 * cubevec.y * cubevec.y - 1.0) * 1.0 / 4.0;
-				}
-				else if (shnbr == 7) {
-					shcoef = 1.092548 * cubevec.x * cubevec.y * 1.0 / 4.0;
-				}
-				else { /* (shnbr == 8) */
-					shcoef = 0.546274 * (cubevec.x * cubevec.x - cubevec.z * cubevec.z) * 1.0 / 4.0;
-				}
-
-				vec4 sample = textureLod(probeHdr, cubevec, lodBias);
-				sh += sample.rgb * shcoef * weight;
-				weight_accum += weight;
-			}
-		}
-	}
-
-	sh *= M_4PI / weight_accum;
-
-	FragColor = vec4(sh, 1.0);
-}
\ No newline at end of file
diff --git a/source/blender/draw/engines/eevee/shaders/lit_surface_frag.glsl b/source/blender/draw/engines/eevee/shaders/lit_surface_frag.glsl
index 8f11835a1cc..6dd9bbcdf6c 100644
--- a/source/blender/draw/engines/eevee/shaders/lit_surface_frag.glsl
+++ b/source/blender/draw/engines/eevee/shaders/lit_surface_frag.glsl
@@ -1,12 +1,13 @@
 
 uniform int light_count;
 uniform int probe_count;
+uniform int grid_count;
 uniform mat4 ProjectionMatrix;
 uniform mat4 ViewMatrixInverse;
 
 uniform sampler2DArray probeCubes;
+uniform sampler2D irradianceGrid;
 uniform float lodMax;
-uniform vec3 shCoefs[9];
 
 #ifndef UTIL_TEX
 #define UTIL_TEX
@@ -20,6 +21,10 @@ layout(std140) uniform probe_block {
 	ProbeData probes_data[MAX_PROBE];
 };
 
+layout(std140) uniform grid_block {
+	GridData grids_data[MAX_GRID];
+};
+
 layout(std140) uniform light_block {
 	LightData lights_data[MAX_LIGHT];
 };
@@ -305,6 +310,88 @@ float probe_attenuation(vec3 W, ProbeData pd)
 	return fac;
 }
 
+IrradianceData load_irradiance_cell(int cell, vec3 N)
+{
+	/* Keep in sync with diffuse_filter_probe() */
+
+#if defined(IRRADIANCE_CUBEMAP)
+
+	#define AMBIANT_CUBESIZE 8
+	ivec2 cell_co = ivec2(AMBIANT_CUBESIZE);
+	int cell_per_row = textureSize(irradianceGrid, 0).x / cell_co.x;
+	cell_co.x *= cell % cell_per_row;
+	cell_co.y *= cell / cell_per_row;
+
+	vec2 texelSize = 1.0 / vec2(AMBIANT_CUBESIZE);
+
+	vec2 uvs = mapping_octahedron(N, texelSize);
+	uvs *= vec2(AMBIANT_CUBESIZE) / vec2(textureSize(irradianceGrid, 0));
+	uvs += vec2(cell_co) / vec2(textureSize(irradianceGrid, 0));
+
+	IrradianceData ir;
+	ir.color = texture(irradianceGrid, uvs).rgb;
+
+#elif defined(IRRADIANCE_SH_L2)
+
+	ivec2 cell_co = ivec2(3, 3);
+	int cell_per_row = textureSize(irradianceGrid, 0).x / cell_co.x;
+	cell_co.x *= cell % cell_per_row;
+	cell_co.y *= cell / cell_per_row;
+
+	ivec3 ofs = ivec3(0, 1, 2);
+
+	IrradianceData ir;
+	ir.shcoefs[0] = texelFetch(irradianceGrid, cell_co + ofs.xx, 0).rgb;
+	ir.shcoefs[1] = texelFetch(irradianceGrid, cell_co + ofs.yx, 0).rgb;
+	ir.shcoefs[2] = texelFetch(irradianceGrid, cell_co + ofs.zx, 0).rgb;
+	ir.shcoefs[3] = texelFetch(irradianceGrid, cell_co + ofs.xy, 0).rgb;
+	ir.shcoefs[4] = texelFetch(irradianceGrid, cell_co + ofs.yy, 0).rgb;
+	ir.shcoefs[5] = texelFetch(irradianceGrid, cell_co + ofs.zy, 0).rgb;
+	ir.shcoefs[6] = texelFetch(irradianceGrid, cell_co + ofs.xz, 0).rgb;
+	ir.shcoefs[7] = texelFetch(irradianceGrid, cell_co + ofs.yz, 0).rgb;
+	ir.shcoefs[8] = texelFetch(irradianceGrid, cell_co + ofs.zz, 0).rgb;
+
+#else /* defined(IRRADIANCE_HL2) */
+
+	ivec2 cell_co = ivec2(3, 2);
+	int cell_per_row = textureSize(irradianceGrid, 0).x / cell_co.x;
+	cell_co.x *= cell % cell_per_row;
+	cell_co.y *= cell / cell_per_row;
+
+	ivec3 is_negative = ivec3(step(0.0, -N));
+
+	IrradianceData ir;
+	ir.cubesides[0] = texelFetch(irradianceGrid, cell_co + ivec2(0, is_negative.x), 0).rgb;
+	ir.cubesides[1] = texelFetch(irradianceGrid, cell_co + ivec2(1, is_negative.y), 0).rgb;
+	ir.cubesides[2] = texelFetch(irradianceGrid, cell_co + ivec2(2, is_negative.z), 0).rgb;
+
+#endif
+
+	return ir;
+}
+
+vec3 get_cell_color(ivec3 localpos, ivec3 gridres, int offset, vec3 ir_dir)
+{
+	/* Keep in sync with update_irradiance_probe */
+
+	int cell = offset + localpos.z + localpos.y * gridres.z + localpos.x * gridres.z * gridres.y;
+	IrradianceData ir_data = load_irradiance_cell(cell, ir_dir);
+	return compute_irradiance(ir_dir, ir_data);
+}
+
+vec3 trilinear_filtering(vec3 weights,
+	vec3 cell0_col, vec3 cell_x_col, vec3 cell_y_col, vec3 cell_z_col, vec3 cell_xy_col, vec3 cell_xz_col, vec3 cell_yz_col, vec3 cell_xyz_col)
+{
+	vec3 x_mix_0 = mix(cell0_col, cell_x_col, weights.x);
+	vec3 x_mix_y = mix(cell_y_col, cell_xy_col, weights.x);
+	vec3 x_mix_z = mix(cell_z_col, cell_xz_col, weights.x);
+	vec3 x_mix_yz = mix(cell_yz_col, cell_xyz_col, weights.x);
+	vec3 y_mix_0 = mix(x_mix_0, x_mix_y, weights.y);
+	vec3 y_mix_z = mix(x_mix_z, x_mix_yz, weights.y);
+	vec3 z_mix1 = mix(y_mix_0, y_mix_z, weights.z);
+	return z_mix1;
+}
+
 vec3 eevee_surface_lit(vec3 world_normal, vec3 albedo, vec3 f0, float roughness, float ao)
 {
 	roughness = clamp(roughness, 1e-8, 0.9999);
@@ -375,12 +462,71 @@ vec3 eevee_surface_lit(vec3 world_normal, vec3 albedo, vec3 f0, float roughness,
 		}
 	}
 
+	for (int i = 0; i < MAX_GRID && i < grid_count; ++i) {
+		GridData gd = grids_data[i];
+
+		vec3 localpos = (gd.localmat * vec4(sd.W, 1.0)).xyz;
+
+		vec3 localpos_max = vec3(gd.g_resolution + ivec3(1)) - localpos;
+		float fade = min(1.0, min_v3(min(localpos_max, localpos)));
+
+		if (fade > 0.0) {
+			localpos -= 1.0;
+			vec3 localpos_floored = floor(localpos);
+			vec3 trilinear_weight = fract(localpos); /* fract(-localpos) */
+
+			float weight_accum = 0.0;
+			vec3 irradiance_accum = vec3(0.0);
+
+			/* For each neighboor cells */
+			for (int i = 0; i < 8; ++i) {
+				ivec3 offset = ivec3(i, i >> 1, i >> 2) & ivec3(1);
+				vec3 cell_cos = clamp(localpos_floored + vec3(offset), vec3(0.0), vec3(gd.g_resolution) - 1.0);
+
+				/* We need this because we render probes in world space (so we need light vector in WS).
+				 * And rendering them in local probe space is too much problem. */
+				vec3 ws_cell_location = gd.g_corner +
+					(gd.g_increment_x * cell_cos.x +
+					 gd.g_increment_y * cell_cos.y +
+					 gd.g_increment_z * cell_cos.z);
+				vec3 ws_point_to_cell = ws_cell_location - sd.W;
+				vec3 ws_light = normalize(ws_point_to_cell);
+
+				vec3 trilinear = mix(1 - trilinear_weight, trilinear_weight, offset);
+				float weight = trilinear.x * trilinear.y * trilinear.z;
+
+				/* Smooth backface test */
+                // weight *= max(0.005, dot(ws_light, sd.N));
+
+				/* Avoid zero weight */
+				weight = max(0.00001, weight);
+
+				vec3 color = get_cell_color(ivec3(cell_cos), gd.g_resolution, gd.g_offset, sd.N);
+
+				weight_accum += weight;
+				irradiance_accum += color * weight;
+			}
+
+			vec3 indirect_diffuse = irradiance_accum / weight_accum;
+
+			// float influ_diff = min(fade, (1.0 - spec_accum.a));
+			float influ_diff = min(1.0, (1.0 - spec_accum.a));
+
+			diff_accum.rgb += indirect_diffuse * influ_diff;
+			diff_accum.a += influ_diff;
+
+			// return texture(irradianceGrid, sd.W.xy).rgb;
+		}
+	}
+
 	/* World probe */
 	if (spec_accum.a < 1.0 || diff_accum.a < 1.0) {
 		ProbeData pd = probes_data[0];
 
+		IrradianceData ir_data = load_irradiance_cell(0, sd.N);
+
 		vec3 spec = textureLod_octahedron(probeCubes, vec4(spec_dir, 0), roughness * lodMax).rgb;
-		vec3 diff = spherical_harmonics(sd.N, pd.shcoefs);
+		vec3 diff = compute_irradiance(sd.N, ir_data);
 
 		diff_accum.rgb += diff * (1.0 - diff_accum.a);
 		spec_accum.rgb += spec * (1.0 - spec_accum.a);
diff --git a/source/blender/draw/intern/DRW_render.h b/source/blender/draw/intern/DRW_render.h
index 37b67cd1237..71b0396dc49 100644
--- a/source/blender/draw/intern/DRW_render.h
+++ b/source/blender/draw/intern/DRW_render.h
@@ -201,7 +201,7 @@ void DRW_framebuffer_texture_attach(struct GPUFrameBuffer *fb, struct GPUTexture
 void DRW_framebuffer_cubeface_attach(struct GPUFrameBuffer *fb, struct GPUTexture *tex, int slot, int face, int mip);
 void DRW_framebuffer_texture_detach(struct GPUTexture *tex);
 void DRW_framebuffer_blit(struct GPUFrameBuffer *fb_read, struct GPUFrameBuffer *fb_write, bool depth);
-void DRW_framebuffer_viewport_size(struct GPUFrameBuffer *UNUSED(fb_read), int w, int h);
+void DRW_framebuffer_viewport_size(struct GPUFrameBuffer *fb_read, int x, int y, int w, int h);
 void DRW_framebuffer_free(struct GPUFrameBuffer *fb);
 #define DRW_FRAMEBUFFER_FREE_SAFE(fb) do { \
 	if (fb != NULL) { \
diff --git a/source/blender/draw/intern/draw_manager.c b/source/blender/draw/intern/draw_manager.c
index 77206a256f2..62a95bcc22b 100644
--- a/source/blender/draw/intern/draw_manager.c
+++ b/source/blender/draw/intern/draw_manager.c
@@ -2103,9 +2103,9 @@ void DRW_framebuffer_blit(struct GPUFrameBuffer *fb_read, struct GPUFrameBuffer
 	GPU_framebuffer_blit(fb_read, 0, fb_write, 0, depth);
 }
 
-void DRW_framebuffer_viewport_size(struct GPUFrameBuffer *UNUSED(fb_read), int w, int h)
+void DRW_framebuffer_viewport_size(struct GPUFrameBuffer *UNUSED(fb_read), int x, int y, int w, int h)
 {
-	glViewport(0, 0, w, h);
+	glViewport(x, y, w, h);
 }
 
 /* Use color management profile to draw texture to framebuffer */