Eevee: Add support for volumetrics in node tree.

Only volume scatter is implemented for now.

8 files changed, 150 insertions, 65 deletions

diff --git a/source/blender/draw/engines/eevee/eevee_effects.c b/source/blender/draw/engines/eevee/eevee_effects.c
index 96b168cdeee..7150cac6add 100644
--- a/source/blender/draw/engines/eevee/eevee_effects.c
+++ b/source/blender/draw/engines/eevee/eevee_effects.c
@@ -32,6 +32,7 @@
 #include "DNA_camera_types.h"
 #include "DNA_screen_types.h"
 #include "DNA_view3d_types.h"
+#include "DNA_world_types.h"
 
 #include "BKE_camera.h"
 #include "BKE_object.h"
@@ -402,14 +403,17 @@ void EEVEE_effects_init(EEVEE_Data *vedata)
 	                    &tex, 1);
 
 	if (BKE_collection_engine_property_value_get_bool(props, "volumetric_enable")) {
-		/* MinMax Pyramid */
+		/* Integration result */
 		DRWFboTexture tex_vol = {&stl->g_data->volumetric, DRW_TEX_RGBA_16, DRW_TEX_MIPMAP | DRW_TEX_FILTER | DRW_TEX_TEMP};
 
 		DRW_framebuffer_init(&fbl->volumetric_fb, &draw_engine_eevee_type,
 		                    (int)viewport_size[0] / 2, (int)viewport_size[1] / 2,
 		                    &tex_vol, 1);
 
-		effects->enabled_effects |= EFFECT_VOLUMETRIC;
+		World *wo = scene->world;
+		if ((wo != NULL) && (wo->use_nodes != NULL) && (wo->nodetree != NULL)) {
+			effects->enabled_effects |= EFFECT_VOLUMETRIC;
+		}
 	}
 }
 
@@ -441,27 +445,38 @@ void EEVEE_effects_cache_init(EEVEE_SceneLayerData *sldata, EEVEE_Data *vedata)
 
 	struct Gwn_Batch *quad = DRW_cache_fullscreen_quad_get();
 
-	{
-		struct GPUShader *sh = EEVEE_material_world_volume_get(NULL, NULL);
-		psl->volumetric_integrate_ps = DRW_pass_create("Volumetric Integration", DRW_STATE_WRITE_COLOR);
-		DRWShadingGroup *grp = DRW_shgroup_create(sh, psl->volumetric_integrate_ps);
-		DRW_shgroup_uniform_buffer(grp, "depthFull", &e_data.depth_src);
-		DRW_shgroup_uniform_buffer(grp, "shadowCubes", &sldata->shadow_depth_cube_pool);
-		DRW_shgroup_uniform_buffer(grp, "irradianceGrid", &sldata->irradiance_pool);
-		DRW_shgroup_uniform_block(grp, "light_block", sldata->light_ubo);
-		DRW_shgroup_uniform_block(grp, "grid_block", sldata->grid_ubo);
-		DRW_shgroup_uniform_block(grp, "shadow_block", sldata->shadow_ubo);
-		DRW_shgroup_uniform_int(grp, "light_count", &sldata->lamps->num_light, 1);
-		DRW_shgroup_uniform_int(grp, "grid_count", &sldata->probes->num_render_grid, 1);
-		DRW_shgroup_uniform_texture(grp, "utilTex", EEVEE_materials_get_util_tex());
-		DRW_shgroup_uniform_vec4(grp, "viewvecs[0]", (float *)stl->g_data->viewvecs, 2);
-		DRW_shgroup_call_add(grp, quad, NULL);
+	if ((effects->enabled_effects & EFFECT_VOLUMETRIC) != 0) {
+		const DRWContextState *draw_ctx = DRW_context_state_get();
+		Scene *scene = draw_ctx->scene;
+		struct World *wo = scene->world; /* Already checked non NULL */
 
-		psl->volumetric_resolve_ps = DRW_pass_create("Volumetric Resolve", DRW_STATE_WRITE_COLOR | DRW_STATE_TRANSMISSION);
-		grp = DRW_shgroup_create(e_data.volumetric_upsample_sh, psl->volumetric_resolve_ps);
-		DRW_shgroup_uniform_buffer(grp, "depthFull", &e_data.depth_src);
-		DRW_shgroup_uniform_buffer(grp, "volumetricBuffer", &stl->g_data->volumetric);
-		DRW_shgroup_call_add(grp, quad, NULL);
+		struct GPUMaterial *mat = EEVEE_material_world_volume_get(scene, wo);
+		psl->volumetric_integrate_ps = DRW_pass_create("Volumetric Integration", DRW_STATE_WRITE_COLOR);
+		DRWShadingGroup *grp = DRW_shgroup_material_create(mat, psl->volumetric_integrate_ps);
+
+		if (grp != NULL) {
+			DRW_shgroup_uniform_buffer(grp, "depthFull", &e_data.depth_src);
+			DRW_shgroup_uniform_buffer(grp, "shadowCubes", &sldata->shadow_depth_cube_pool);
+			DRW_shgroup_uniform_buffer(grp, "irradianceGrid", &sldata->irradiance_pool);
+			DRW_shgroup_uniform_block(grp, "light_block", sldata->light_ubo);
+			DRW_shgroup_uniform_block(grp, "grid_block", sldata->grid_ubo);
+			DRW_shgroup_uniform_block(grp, "shadow_block", sldata->shadow_ubo);
+			DRW_shgroup_uniform_int(grp, "light_count", &sldata->lamps->num_light, 1);
+			DRW_shgroup_uniform_int(grp, "grid_count", &sldata->probes->num_render_grid, 1);
+			DRW_shgroup_uniform_texture(grp, "utilTex", EEVEE_materials_get_util_tex());
+			DRW_shgroup_uniform_vec4(grp, "viewvecs[0]", (float *)stl->g_data->viewvecs, 2);
+			DRW_shgroup_call_add(grp, quad, NULL);
+
+			psl->volumetric_resolve_ps = DRW_pass_create("Volumetric Resolve", DRW_STATE_WRITE_COLOR | DRW_STATE_TRANSMISSION);
+			grp = DRW_shgroup_create(e_data.volumetric_upsample_sh, psl->volumetric_resolve_ps);
+			DRW_shgroup_uniform_buffer(grp, "depthFull", &e_data.depth_src);
+			DRW_shgroup_uniform_buffer(grp, "volumetricBuffer", &stl->g_data->volumetric);
+			DRW_shgroup_call_add(grp, quad, NULL);
+		}
+		else {
+			/* Compilation failled */
+			effects->enabled_effects &= ~EFFECT_VOLUMETRIC;
+		}
 	}
 
 	{
diff --git a/source/blender/draw/engines/eevee/eevee_lightprobes.c b/source/blender/draw/engines/eevee/eevee_lightprobes.c
index ee518cc268c..5ae60ff4ef6 100644
--- a/source/blender/draw/engines/eevee/eevee_lightprobes.c
+++ b/source/blender/draw/engines/eevee/eevee_lightprobes.c
@@ -73,7 +73,6 @@ static struct {
 
 extern char datatoc_background_vert_glsl[];
 extern char datatoc_default_world_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[];
diff --git a/source/blender/draw/engines/eevee/eevee_materials.c b/source/blender/draw/engines/eevee/eevee_materials.c
index f7c28530aef..c35b94e8105 100644
--- a/source/blender/draw/engines/eevee/eevee_materials.c
+++ b/source/blender/draw/engines/eevee/eevee_materials.c
@@ -63,8 +63,8 @@
 /* *********** STATIC *********** */
 static struct {
 	char *frag_shader_lib;
+	char *volume_shader_lib;
 
-	struct GPUShader *default_volume_sh;
 	struct GPUShader *default_prepass_sh;
 	struct GPUShader *default_prepass_clip_sh;
 	struct GPUShader *default_lit[VAR_MAT_MAX];
@@ -273,6 +273,12 @@ void EEVEE_materials_init(EEVEE_StorageList *stl)
 
 		ds_frag = BLI_dynstr_new();
 		BLI_dynstr_append(ds_frag, e_data.frag_shader_lib);
+		BLI_dynstr_append(ds_frag, datatoc_volumetric_frag_glsl);
+		e_data.volume_shader_lib = BLI_dynstr_get_cstring(ds_frag);
+		BLI_dynstr_free(ds_frag);
+
+		ds_frag = BLI_dynstr_new();
+		BLI_dynstr_append(ds_frag, e_data.frag_shader_lib);
 		BLI_dynstr_append(ds_frag, datatoc_default_frag_glsl);
 		frag_str = BLI_dynstr_get_cstring(ds_frag);
 		BLI_dynstr_free(ds_frag);
@@ -290,16 +296,6 @@ void EEVEE_materials_init(EEVEE_StorageList *stl)
 
 		MEM_freeN(frag_str);
 
-		ds_frag = BLI_dynstr_new();
-		BLI_dynstr_append(ds_frag, e_data.frag_shader_lib);
-		BLI_dynstr_append(ds_frag, datatoc_volumetric_frag_glsl);
-		frag_str = BLI_dynstr_get_cstring(ds_frag);
-		BLI_dynstr_free(ds_frag);
-
-		e_data.default_volume_sh = DRW_shader_create_fullscreen(frag_str, SHADER_DEFINES "#define STEP_INTEGRATE\n");
-
-		MEM_freeN(frag_str);
-
 		/* Textures */
 		const int layers = 3;
 		float (*texels)[4] = MEM_mallocN(sizeof(float[4]) * 64 * 64 * layers, "utils texels");
@@ -403,9 +399,19 @@ struct GPUMaterial *EEVEE_material_world_background_get(struct Scene *scene, Wor
 	        SHADER_DEFINES "#define WORLD_BACKGROUND\n");
 }
 
-struct GPUShader *EEVEE_material_world_volume_get(struct Scene *UNUSED(scene), World *UNUSED(wo))
+struct GPUMaterial *EEVEE_material_world_volume_get(struct Scene *scene, World *wo)
 {
-	return e_data.default_volume_sh;
+	const void *engine = &DRW_engine_viewport_eevee_type;
+	int options = VAR_WORLD_VOLUME;
+
+	GPUMaterial *mat = GPU_material_from_nodetree_find(&wo->gpumaterial, engine, options);
+	if (mat != NULL) {
+		return mat;
+	}
+	return GPU_material_from_nodetree(
+	        scene, wo->nodetree, &wo->gpumaterial, engine, options,
+	        datatoc_background_vert_glsl, NULL, e_data.volume_shader_lib,
+	        SHADER_DEFINES "#define VOLUMETRICS\n");
 }
 
 struct GPUMaterial *EEVEE_material_mesh_get(
@@ -785,7 +791,7 @@ void EEVEE_materials_free(void)
 		DRW_SHADER_FREE_SAFE(e_data.default_lit[i]);
 	}
 	MEM_SAFE_FREE(e_data.frag_shader_lib);
-	DRW_SHADER_FREE_SAFE(e_data.default_volume_sh);
+	MEM_SAFE_FREE(e_data.volume_shader_lib);
 	DRW_SHADER_FREE_SAFE(e_data.default_prepass_sh);
 	DRW_SHADER_FREE_SAFE(e_data.default_prepass_clip_sh);
 	DRW_SHADER_FREE_SAFE(e_data.default_background);
diff --git a/source/blender/draw/engines/eevee/eevee_private.h b/source/blender/draw/engines/eevee/eevee_private.h
index 727edfb9607..adfa598b91c 100644
--- a/source/blender/draw/engines/eevee/eevee_private.h
+++ b/source/blender/draw/engines/eevee/eevee_private.h
@@ -50,6 +50,7 @@ extern struct DrawEngineType draw_engine_eevee_type;
 enum {
 	VAR_WORLD_BACKGROUND,
 	VAR_WORLD_PROBE,
+	VAR_WORLD_VOLUME,
 };
 
 /* Material shader variations */
@@ -424,7 +425,7 @@ void EEVEE_materials_cache_populate(EEVEE_Data *vedata, EEVEE_SceneLayerData *sl
 void EEVEE_materials_cache_finish(EEVEE_Data *vedata);
 struct GPUMaterial *EEVEE_material_world_lightprobe_get(struct Scene *scene, struct World *wo);
 struct GPUMaterial *EEVEE_material_world_background_get(struct Scene *scene, struct World *wo);
-struct GPUShader *EEVEE_material_world_volume_get(struct Scene *scene, struct World *wo);
+struct GPUMaterial *EEVEE_material_world_volume_get(struct Scene *scene, struct World *wo);
 struct GPUMaterial *EEVEE_material_mesh_lightprobe_get(struct Scene *scene, Material *ma);
 struct GPUMaterial *EEVEE_material_mesh_get(struct Scene *scene, Material *ma, bool use_ao, bool use_bent_normals);
 struct GPUMaterial *EEVEE_material_hair_get(struct Scene *scene, Material *ma, bool use_ao, bool use_bent_normals);
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 6f255583340..2c72df16135 100644
--- a/source/blender/draw/engines/eevee/shaders/bsdf_common_lib.glsl
+++ b/source/blender/draw/engines/eevee/shaders/bsdf_common_lib.glsl
@@ -17,6 +17,44 @@ uniform vec4 viewvecs[2];
 #define cameraPos       ViewMatrixInverse[3].xyz
 
 /* ------- Structures -------- */
+#ifdef VOLUMETRICS
+
+#define NODETREE_EXEC
+
+struct Closure {
+	vec3 absorption;
+	vec3 scatter;
+	vec3 emission;
+	float anisotropy;
+};
+
+#define CLOSURE_DEFAULT Closure(vec3(0.0), vec3(0.0), vec3(0.0), 0.0);
+
+Closure closure_mix(Closure cl1, Closure cl2, float fac)
+{
+	Closure cl;
+	cl.absorption = mix(cl1.absorption, cl2.absorption, fac);
+	cl.scatter = mix(cl1.scatter, cl2.scatter, fac);
+	cl.emission = mix(cl1.emission, cl2.emission, fac);
+	cl.anisotropy = mix(cl1.anisotropy, cl2.anisotropy, fac);
+	return cl;
+}
+
+Closure closure_add(Closure cl1, Closure cl2)
+{
+	Closure cl;
+	cl.absorption = cl1.absorption + cl2.absorption;
+	cl.scatter = cl1.scatter + cl2.scatter;
+	cl.emission = cl1.emission + cl2.emission;
+	cl.anisotropy = cl1.anisotropy + cl2.anisotropy;
+	return cl;
+}
+
+Closure nodetree_exec(void); /* Prototype */
+
+
+#endif /* VOLUMETRICS */
+
 
 struct LightData {
 	vec4 position_influence;      /* w : InfluenceRadius */
diff --git a/source/blender/draw/engines/eevee/shaders/volumetric_frag.glsl b/source/blender/draw/engines/eevee/shaders/volumetric_frag.glsl
index 8e7393a2f58..fe80fed232f 100644
--- a/source/blender/draw/engines/eevee/shaders/volumetric_frag.glsl
+++ b/source/blender/draw/engines/eevee/shaders/volumetric_frag.glsl
@@ -1,34 +1,17 @@
 
 out vec4 FragColor;
 
-#ifdef STEP_INTEGRATE
+#ifdef VOLUMETRICS
 
 uniform sampler2D depthFull;
 
-float find_next_step(float near, float far, float noise, int iter, int iter_count)
-{
-	const float lambda = 0.8f; /* TODO : Parameter */
-
-	float progress = (float(iter) + noise) / float(iter_count);
-
-	float linear_split = mix(near, far, progress);
-
-	if (ProjectionMatrix[3][3] == 0.0) {
-		float exp_split = near * pow(far / near, progress);
-		return mix(linear_split, exp_split, lambda);
-	}
-	else {
-		return linear_split;
-	}
-}
-
 void participating_media_properties(vec3 wpos, out vec3 absorption, out vec3 scattering, out float anisotropy)
 {
-	/* TODO Call nodetree from here. */
-	absorption = vec3(0.00);
-	scattering = vec3(1.0) * step(-1.0, -wpos.z);
+	Closure cl = nodetree_exec();
 
-	anisotropy = -0.8;
+	absorption = cl.absorption;
+	scattering = cl.scatter;
+	anisotropy = cl.anisotropy;
 }
 
 float phase_function_isotropic()
@@ -38,7 +21,7 @@ float phase_function_isotropic()
 
 float phase_function(vec3 v, vec3 l, float g)
 {
-#if 0
+#if 1
 	/* Henyey-Greenstein */
 	float cos_theta = dot(v, l);
 	float sqr_g = g * g;
@@ -54,6 +37,23 @@ vec3 light_volume(LightData ld, vec4 l_vector, vec3 l_col)
 	return l_col * (4.0 * ld.l_radius * ld.l_radius * M_PI * M_PI) / (dist * dist);
 }
 
+float find_next_step(float near, float far, float noise, int iter, int iter_count)
+{
+	const float lambda = 0.8f; /* TODO : Parameter */
+
+	float progress = (float(iter) + noise) / float(iter_count);
+
+	float linear_split = mix(near, far, progress);
+
+	if (ProjectionMatrix[3][3] == 0.0) {
+		float exp_split = near * pow(far / near, progress);
+		return mix(linear_split, exp_split, lambda);
+	}
+	else {
+		return linear_split;
+	}
+}
+
 /* Based on Frosbite Unified Volumetric.
  * https://www.ea.com/frostbite/news/physically-based-unified-volumetric-rendering-in-frostbite */
 void main()
diff --git a/source/blender/gpu/shaders/gpu_shader_material.glsl b/source/blender/gpu/shaders/gpu_shader_material.glsl
index afe862bb70f..5765644cd2b 100644
--- a/source/blender/gpu/shaders/gpu_shader_material.glsl
+++ b/source/blender/gpu/shaders/gpu_shader_material.glsl
@@ -2653,8 +2653,8 @@ layout(std140) uniform lightSource {
 	glLight glLightSource[NUM_LIGHTS];
 };
 
+#ifndef VOLUMETRICS
 /* bsdfs */
-
 void node_bsdf_diffuse(vec4 color, float roughness, vec3 N, out Closure result)
 {
 	/* ambient light */
@@ -2905,13 +2905,18 @@ void node_ambient_occlusion(vec4 color, out Closure result)
 {
 	result = Closure(color.rgb, color.a);
 }
+#endif /* VOLUMETRICS */
 
 /* emission */
 
 void node_emission(vec4 color, float strength, vec3 N, out Closure result)
 {
+#ifndef VOLUMETRICS
 	color *= strength;
 	result = Closure(color.rgb, color.a);
+#else
+	result = Closure(vec3(0.0), vec3(0.0), color.rgb * strength, 0.0);
+#endif
 }
 
 /* background */
@@ -2931,8 +2936,23 @@ void background_transform_to_world(vec3 viewvec, out vec3 worldvec)
 
 void node_background(vec4 color, float strength, out Closure result)
 {
+#ifndef VOLUMETRICS
 	color *= strength;
 	result = Closure(color.rgb, color.a);
+#else
+	result = CLOSURE_DEFAULT;
+#endif
+}
+
+/* volumes */
+
+void node_volume_scatter(vec4 color, float density, float anisotropy, out Closure result)
+{
+#ifdef VOLUMETRICS
+	result = Closure(vec3(0.0), color.rgb * density, vec3(0.0), anisotropy);
+#else
+	result = CLOSURE_DEFAULT;
+#endif
 }
 
 /* closures */
@@ -3947,9 +3967,14 @@ uniform float backgroundAlpha;
 
 void node_output_world(Closure surface, Closure volume, out Closure result)
 {
+#ifndef VOLUMETRICS
 	result = Closure(surface.radiance, backgroundAlpha);
+#else
+	result = volume;
+#endif /* VOLUMETRICS */
 }
 
+#ifndef VOLUMETRICS
 /* TODO : clean this ifdef mess */
 /* EEVEE output */
 #ifdef EEVEE_ENGINE
@@ -3982,7 +4007,8 @@ void node_output_eevee_material(Closure surface, out Closure result)
 	result = Closure(surface.radiance, length(viewPosition));
 }
 
-#endif
+#endif /* EEVEE_ENGINE */
+#endif /* VOLUMETRICS */
 
 /* ********************** matcap style render ******************** */
 
diff --git a/source/blender/nodes/shader/nodes/node_shader_volume_scatter.c b/source/blender/nodes/shader/nodes/node_shader_volume_scatter.c
index 0c5647b4ba8..4fb1188c1d2 100644
--- a/source/blender/nodes/shader/nodes/node_shader_volume_scatter.c
+++ b/source/blender/nodes/shader/nodes/node_shader_volume_scatter.c
@@ -41,9 +41,9 @@ static bNodeSocketTemplate sh_node_volume_scatter_out[] = {
 	{	-1, 0, ""	}
 };
 
-static int node_shader_gpu_volume_scatter(GPUMaterial *UNUSED(mat), bNode *UNUSED(node), bNodeExecData *UNUSED(execdata), GPUNodeStack *UNUSED(in), GPUNodeStack *UNUSED(out))
+static int node_shader_gpu_volume_scatter(GPUMaterial *mat, bNode *UNUSED(node), bNodeExecData *UNUSED(execdata), GPUNodeStack *in, GPUNodeStack *out)
 {
-	return false;
+	return GPU_stack_link(mat, "node_volume_scatter", in, out);
 }
 
 /* node type definition */