Eevee: Add mist pass support.

Eevee: Render: Fix crash when not enabling mist pass.

6 files changed, 215 insertions, 0 deletions

diff --git a/source/blender/draw/CMakeLists.txt b/source/blender/draw/CMakeLists.txt
index 1bff4b875ce..51b3db695c2 100644
--- a/source/blender/draw/CMakeLists.txt
+++ b/source/blender/draw/CMakeLists.txt
@@ -92,6 +92,7 @@ set(SRC
 	engines/eevee/eevee_lightprobes.c
 	engines/eevee/eevee_lights.c
 	engines/eevee/eevee_materials.c
+	engines/eevee/eevee_mist.c
 	engines/eevee/eevee_motion_blur.c
 	engines/eevee/eevee_occlusion.c
 	engines/eevee/eevee_render.c
@@ -161,6 +162,7 @@ data_to_c_simple(engines/eevee/shaders/effect_downsample_frag.glsl SRC)
 data_to_c_simple(engines/eevee/shaders/effect_downsample_cube_frag.glsl SRC)
 data_to_c_simple(engines/eevee/shaders/effect_gtao_frag.glsl SRC)
 data_to_c_simple(engines/eevee/shaders/effect_minmaxz_frag.glsl SRC)
+data_to_c_simple(engines/eevee/shaders/effect_mist_frag.glsl SRC)
 data_to_c_simple(engines/eevee/shaders/effect_motion_blur_frag.glsl SRC)
 data_to_c_simple(engines/eevee/shaders/effect_ssr_frag.glsl SRC)
 data_to_c_simple(engines/eevee/shaders/effect_subsurface_frag.glsl SRC)
diff --git a/source/blender/draw/engines/eevee/eevee_engine.c b/source/blender/draw/engines/eevee/eevee_engine.c
index a8dafe1ca7a..6c0d71a7432 100644
--- a/source/blender/draw/engines/eevee/eevee_engine.c
+++ b/source/blender/draw/engines/eevee/eevee_engine.c
@@ -390,6 +390,7 @@ static void eevee_engine_free(void)
 	EEVEE_lightprobes_free();
 	EEVEE_lights_free();
 	EEVEE_materials_free();
+	EEVEE_mist_free();
 	EEVEE_motion_blur_free();
 	EEVEE_occlusion_free();
 	EEVEE_screen_raytrace_free();
diff --git a/source/blender/draw/engines/eevee/eevee_mist.c b/source/blender/draw/engines/eevee/eevee_mist.c
new file mode 100644
index 00000000000..ba9157a7f91
--- /dev/null
+++ b/source/blender/draw/engines/eevee/eevee_mist.c
@@ -0,0 +1,135 @@
+/*
+ * Copyright 2016, Blender Foundation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * Contributor(s): Blender Institute
+ *
+ */
+
+/** \file eevee_mist.c
+ *  \ingroup draw_engine
+ *
+ * Implementation of Blender Mist pass.
+ * IMPORTANT: This is a "post process" of the Z depth so it will lack any transparent objects.
+ */
+
+#include "DRW_engine.h"
+#include "DRW_render.h"
+
+#include "DNA_world_types.h"
+
+#include "BLI_string_utils.h"
+
+#include "eevee_private.h"
+
+extern char datatoc_common_uniforms_lib_glsl[];
+extern char datatoc_bsdf_common_lib_glsl[];
+extern char datatoc_effect_mist_frag_glsl[];
+
+static struct {
+	struct GPUShader *mist_sh;
+} e_data = {NULL}; /* Engine data */
+
+void EEVEE_mist_output_init(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedata)
+{
+	const DRWContextState *draw_ctx = DRW_context_state_get();
+	EEVEE_FramebufferList *fbl = vedata->fbl;
+	DefaultTextureList *dtxl = DRW_viewport_texture_list_get();
+	EEVEE_TextureList *txl = vedata->txl;
+	EEVEE_StorageList *stl = vedata->stl;
+	EEVEE_PassList *psl = vedata->psl;
+	EEVEE_PrivateData *g_data = stl->g_data;
+	Scene *scene = draw_ctx->scene;
+
+	const float *viewport_size = DRW_viewport_size_get();
+	float clear[4] = {0.0f, 0.0f, 0.0f, 0.0f};
+
+	if (e_data.mist_sh == NULL) {
+		char *frag_str = BLI_string_joinN(
+		        datatoc_common_uniforms_lib_glsl,
+		        datatoc_bsdf_common_lib_glsl,
+		        datatoc_effect_mist_frag_glsl);
+
+		e_data.mist_sh = DRW_shader_create_fullscreen(frag_str, "#define FIRST_PASS\n");
+
+		MEM_freeN(frag_str);
+	}
+
+	/* Create FrameBuffer. */
+	DRWFboTexture tex_data = {&txl->mist_accum, DRW_TEX_R_32, 0}; /* Should be enough precision for many samples. */
+	DRW_framebuffer_init(&fbl->mist_accum_fb, &draw_engine_eevee_type, (int)viewport_size[0], (int)viewport_size[1],
+	                     &tex_data, 1);
+
+	/* Clear texture. */
+	DRW_framebuffer_bind(fbl->mist_accum_fb);
+	DRW_framebuffer_clear(true, false, false, clear, 0.0f);
+
+	/* Mist settings. */
+	if (scene && scene->world) {
+		g_data->mist_start = scene->world->miststa;
+		g_data->mist_inv_dist = (scene->world->mistdist > 0.0f) ? 1.0f / scene->world->mistdist : 0.0f;
+
+		switch (scene->world->mistype) {
+			case WO_MIST_QUADRATIC:
+				g_data->mist_falloff = 2.0f;
+				break;
+			case WO_MIST_LINEAR:
+				g_data->mist_falloff = 1.0f;
+				break;
+			case WO_MIST_INVERSE_QUADRATIC:
+				g_data->mist_falloff = 0.5f;
+				break;
+		}
+	}
+	else {
+		float near = -sldata->common_data.view_vecs[0][2];
+		float range = sldata->common_data.view_vecs[1][2];
+		/* Fallback */
+		g_data->mist_start = near;
+		g_data->mist_inv_dist = 1.0f / fabsf(range);
+		g_data->mist_falloff = 1.0f;
+	}
+
+	/* XXX ??!! WHY? If not it does not match cycles. */
+	g_data->mist_falloff *= 0.5f;
+
+	/* Create Pass and shgroup. */
+	psl->mist_accum_ps = DRW_pass_create("Mist Accum", DRW_STATE_WRITE_COLOR | DRW_STATE_ADDITIVE);
+	DRWShadingGroup *grp = DRW_shgroup_create(e_data.mist_sh, psl->mist_accum_ps);
+	DRW_shgroup_uniform_buffer(grp, "depthBuffer", &dtxl->depth);
+	DRW_shgroup_uniform_block(grp, "common_block", sldata->common_ubo);
+	DRW_shgroup_uniform_vec3(grp, "mistSettings", &g_data->mist_start, 1);
+	DRW_shgroup_call_add(grp, DRW_cache_fullscreen_quad_get(), NULL);
+}
+
+void EEVEE_mist_output_accumulate(EEVEE_ViewLayerData *UNUSED(sldata), EEVEE_Data *vedata)
+{
+	EEVEE_FramebufferList *fbl = vedata->fbl;
+	EEVEE_PassList *psl = vedata->psl;
+
+	if (fbl->mist_accum_fb != NULL) {
+		DRW_framebuffer_bind(fbl->mist_accum_fb);
+		DRW_draw_pass(psl->mist_accum_ps);
+
+		/* Restore */
+		DRW_framebuffer_bind(fbl->main);
+	}
+}
+
+void EEVEE_mist_free(void)
+{
+	DRW_SHADER_FREE_SAFE(e_data.mist_sh);
+}
diff --git a/source/blender/draw/engines/eevee/eevee_private.h b/source/blender/draw/engines/eevee/eevee_private.h
index 1c35d5e7262..6a4a99fb1b0 100644
--- a/source/blender/draw/engines/eevee/eevee_private.h
+++ b/source/blender/draw/engines/eevee/eevee_private.h
@@ -160,6 +160,7 @@ typedef struct EEVEE_PassList {
 	struct DRWPass *ao_horizon_search;
 	struct DRWPass *ao_horizon_search_layer;
 	struct DRWPass *ao_horizon_debug;
+	struct DRWPass *mist_accum_ps;
 	struct DRWPass *motion_blur;
 	struct DRWPass *bloom_blit;
 	struct DRWPass *bloom_downsample_first;
@@ -230,6 +231,7 @@ typedef struct EEVEE_FramebufferList {
 	struct GPUFrameBuffer *volumetric_integ_fb;
 	struct GPUFrameBuffer *screen_tracing_fb;
 	struct GPUFrameBuffer *refract_fb;
+	struct GPUFrameBuffer *mist_accum_fb;
 
 	struct GPUFrameBuffer *update_noise_fb;
 
@@ -251,6 +253,7 @@ typedef struct EEVEE_TextureList {
 	struct GPUTexture *bloom_blit; /* R16_G16_B16 */
 	struct GPUTexture *bloom_downsample[MAX_BLOOM_STEP]; /* R16_G16_B16 */
 	struct GPUTexture *bloom_upsample[MAX_BLOOM_STEP - 1]; /* R16_G16_B16 */
+	struct GPUTexture *mist_accum;
 	struct GPUTexture *sss_dir_accum;
 	struct GPUTexture *sss_col_accum;
 	struct GPUTexture *ssr_normal_input;
@@ -740,6 +743,8 @@ typedef struct EEVEE_PrivateData {
 	float persmat[4][4], persinv[4][4];
 	float viewmat[4][4], viewinv[4][4];
 	float winmat[4][4], wininv[4][4];
+	/* Mist Settings */
+	float mist_start, mist_inv_dist, mist_falloff;
 } EEVEE_PrivateData; /* Transient data */
 
 /* eevee_data.c */
@@ -838,6 +843,11 @@ void EEVEE_motion_blur_cache_init(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedat
 void EEVEE_motion_blur_draw(EEVEE_Data *vedata);
 void EEVEE_motion_blur_free(void);
 
+/* eevee_mist.c */
+void EEVEE_mist_output_init(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedata);
+void EEVEE_mist_output_accumulate(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedata);;
+void EEVEE_mist_free(void);
+
 /* eevee_temporal_sampling.c */
 int EEVEE_temporal_sampling_init(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedata);
 void EEVEE_temporal_sampling_matrices_calc(
diff --git a/source/blender/draw/engines/eevee/eevee_render.c b/source/blender/draw/engines/eevee/eevee_render.c
index e3d6d182053..b4a0986b56c 100644
--- a/source/blender/draw/engines/eevee/eevee_render.c
+++ b/source/blender/draw/engines/eevee/eevee_render.c
@@ -167,6 +167,11 @@ static void eevee_render_result_subsurface(
 	const DRWContextState *draw_ctx = DRW_context_state_get();
 	ViewLayer *view_layer = draw_ctx->view_layer;
 
+	if (vedata->fbl->sss_accum_fb == NULL) {
+		/* SSS is not enabled. */
+		return;
+	}
+
 	if ((view_layer->passflag & SCE_PASS_SUBSURFACE_COLOR) != 0) {
 		RenderLayer *rl = rr->layers.first;
 		RenderPass *rp = RE_pass_find_by_name(rl, RE_PASSNAME_SUBSURFACE_COLOR, viewname);
@@ -282,6 +287,30 @@ static void eevee_render_result_z(
 	}
 }
 
+static void eevee_render_result_mist(
+        RenderResult *rr, const char *viewname,
+        EEVEE_Data *vedata, EEVEE_ViewLayerData *UNUSED(sldata))
+{
+	const DRWContextState *draw_ctx = DRW_context_state_get();
+	ViewLayer *view_layer = draw_ctx->view_layer;
+
+	if ((view_layer->passflag & SCE_PASS_MIST) != 0) {
+		RenderLayer *rl = rr->layers.first;
+		RenderPass *rp = RE_pass_find_by_name(rl, RE_PASSNAME_MIST, viewname);
+
+		IDProperty *props = BKE_view_layer_engine_evaluated_get(view_layer, COLLECTION_MODE_NONE, RE_engine_id_BLENDER_EEVEE);
+		float render_samples = (float)BKE_collection_engine_property_value_get_int(props, "taa_render_samples");
+
+		DRW_framebuffer_bind(vedata->fbl->mist_accum_fb);
+		DRW_framebuffer_read_data(rr->xof, rr->yof, rr->rectx, rr->recty, 1, 0, rp->rect);
+
+		/* This is the accumulated color. Divide by the number of samples. */
+		for (int i = 0; i < rr->rectx * rr->recty; i++) {
+			rp->rect[i] /= render_samples;
+		}
+	}
+}
+
 void EEVEE_render_draw(EEVEE_Data *vedata, struct RenderEngine *engine, struct Depsgraph *UNUSED(depsgraph))
 {
 	const DRWContextState *draw_ctx = DRW_context_state_get();
@@ -305,6 +334,10 @@ void EEVEE_render_draw(EEVEE_Data *vedata, struct RenderEngine *engine, struct D
 		EEVEE_subsurface_output_init(sldata, vedata);
 	}
 
+	if ((view_layer->passflag & SCE_PASS_MIST) != 0) {
+		EEVEE_mist_output_init(sldata, vedata);
+	}
+
 	/* Init render result. */
 	const char *viewname = NULL;
 	const float *render_size = DRW_viewport_size_get();
@@ -366,6 +399,8 @@ void EEVEE_render_draw(EEVEE_Data *vedata, struct RenderEngine *engine, struct D
 		eevee_render_result_normal(rr, viewname, vedata, sldata);
 		/* Volumetrics Resolve Opaque */
 		EEVEE_volumes_resolve(sldata, vedata);
+		/* Mist output */
+		EEVEE_mist_output_accumulate(sldata, vedata);
 		/* Transparent */
 		DRW_pass_sort_shgroup_z(psl->transparent_pass);
 		DRW_draw_pass(psl->transparent_pass);
@@ -377,6 +412,7 @@ void EEVEE_render_draw(EEVEE_Data *vedata, struct RenderEngine *engine, struct D
 
 	eevee_render_result_combined(rr, viewname, vedata, sldata);
 	eevee_render_result_subsurface(rr, viewname, vedata, sldata);
+	eevee_render_result_mist(rr, viewname, vedata, sldata);
 
 	RE_engine_end_result(engine, rr, false, false, false);
 }
diff --git a/source/blender/draw/engines/eevee/shaders/effect_mist_frag.glsl b/source/blender/draw/engines/eevee/shaders/effect_mist_frag.glsl
new file mode 100644
index 00000000000..fe38b2e9aac
--- /dev/null
+++ b/source/blender/draw/engines/eevee/shaders/effect_mist_frag.glsl
@@ -0,0 +1,31 @@
+/* Convert depth to Mist factor */
+uniform vec3 mistSettings;
+
+#define mistStart         mistSettings.x
+#define mistInvDistance   mistSettings.y
+#define mistFalloff       mistSettings.z
+
+out vec4 fragColor;
+
+void main()
+{
+	vec2 texel_size = 1.0 / vec2(textureSize(depthBuffer, 0)).xy;
+	vec2 uvs = gl_FragCoord.xy * texel_size;
+
+	float depth = textureLod(depthBuffer, uvs, 0.0).r;
+	vec3 co = get_view_space_from_depth(uvs, depth);
+
+	float zcor = (ProjectionMatrix[3][3] == 0.0) ? length(co) : -co.z;
+
+	/* bring depth into 0..1 range */
+	float mist = saturate((zcor - mistStart) * mistInvDistance);
+
+	/* falloff */
+	mist = pow(mist, mistFalloff);
+
+	fragColor = vec4(mist);
+
+	// if (mist > 0.999) fragColor = vec4(1.0);
+	// else if (mist > 0.0001) fragColor = vec4(0.5);
+	// else fragColor = vec4(0.0);
+}