Workbench: Xray: Optimize and fix implementation.

There was a method explained in the Weighted Blended Order-Independent
Transparency paper to support hardware that does not support per render
target blending function.

So now only 2 geometry passes are required instead of 3 (one being the
outline/depth fill pass).

This also fix how the blending is done. There was some premult confusion
in the implementation.

10 files changed, 47 insertions, 153 deletions

diff --git a/source/blender/draw/CMakeLists.txt b/source/blender/draw/CMakeLists.txt
index b7eaecb7ab6..f049fc87205 100644
--- a/source/blender/draw/CMakeLists.txt
+++ b/source/blender/draw/CMakeLists.txt
@@ -227,7 +227,6 @@ data_to_c_simple(engines/workbench/shaders/workbench_deferred_composite_frag.gls
 data_to_c_simple(engines/workbench/shaders/workbench_forward_composite_frag.glsl SRC)
 data_to_c_simple(engines/workbench/shaders/workbench_forward_depth_frag.glsl SRC)
 data_to_c_simple(engines/workbench/shaders/workbench_forward_transparent_accum_frag.glsl SRC)
-data_to_c_simple(engines/workbench/shaders/workbench_forward_transparent_revealage_frag.glsl SRC)
 data_to_c_simple(engines/workbench/shaders/workbench_object_outline_lib.glsl SRC)
 data_to_c_simple(engines/workbench/shaders/workbench_prepass_vert.glsl SRC)
 data_to_c_simple(engines/workbench/shaders/workbench_prepass_frag.glsl SRC)
diff --git a/source/blender/draw/engines/workbench/shaders/workbench_common_lib.glsl b/source/blender/draw/engines/workbench/shaders/workbench_common_lib.glsl
index 8908891d7e6..0b494aa019f 100644
--- a/source/blender/draw/engines/workbench/shaders/workbench_common_lib.glsl
+++ b/source/blender/draw/engines/workbench/shaders/workbench_common_lib.glsl
@@ -65,11 +65,11 @@ void fresnel(vec3 I, vec3 N, float ior, out float kr)
 	// kt = 1 - kr;
 }
 
-vec4 calculate_transparent_accum(vec4 premultiplied) {
-	float a = min(1.0, premultiplied.a) * 8.0 + 0.01;
+float calculate_transparent_weight(float alpha) {
+	/* Eq 10 */
+	float a = min(1.0, alpha) * 8.0 + 0.01;
 	float b = -gl_FragCoord.z * 0.95 + 1.0;
-	float w = clamp(a * a * a * 1e8 * b * b * b, 1e-2, 3e2);
-	return premultiplied * w;
+	return alpha * clamp(a * a * a * 1e8 * b * b * b, 1e-2, 3e3);
 }
 
 vec3 view_vector_from_screen_uv(vec2 uv, vec4 viewvecs[3], mat4 proj_mat)
diff --git a/source/blender/draw/engines/workbench/shaders/workbench_forward_composite_frag.glsl b/source/blender/draw/engines/workbench/shaders/workbench_forward_composite_frag.glsl
index f335e1a15bd..1d9f37274bd 100644
--- a/source/blender/draw/engines/workbench/shaders/workbench_forward_composite_frag.glsl
+++ b/source/blender/draw/engines/workbench/shaders/workbench_forward_composite_frag.glsl
@@ -2,9 +2,7 @@ out vec4 fragColor;
 
 uniform usampler2D objectId;
 uniform sampler2D transparentAccum;
-#ifdef WORKBENCH_REVEALAGE_ENABLED
 uniform sampler2D transparentRevealage;
-#endif
 uniform vec2 invertedViewportSize;
 
 layout(std140) uniform world_block {
@@ -16,29 +14,24 @@ void main()
 	ivec2 texel = ivec2(gl_FragCoord.xy);
 	vec2 uv_viewport = gl_FragCoord.xy * invertedViewportSize;
 	uint object_id = texelFetch(objectId, texel, 0).r;
-	vec4 transparent_accum = texelFetch(transparentAccum, texel, 0);
-#ifdef WORKBENCH_REVEALAGE_ENABLED
-	float transparent_revealage = texelFetch(transparentRevealage, texel, 0).r;
-#endif
-	vec4 color;
-	vec4 bg_color;
+
+	/* Listing 4 */
+	vec4 trans_accum = texelFetch(transparentAccum, texel, 0);
+	float trans_revealage = trans_accum.a;
+	trans_accum.a = texelFetch(transparentRevealage, texel, 0).r;
 
 #ifdef V3D_SHADING_OBJECT_OUTLINE
 	float outline = calculate_object_outline(objectId, texel, object_id);
 #else /* V3D_SHADING_OBJECT_OUTLINE */
 	float outline = 1.0;
 #endif /* V3D_SHADING_OBJECT_OUTLINE */
-	bg_color = vec4(background_color(world_data, uv_viewport.y), 0.0);
-	if (object_id == NO_OBJECT_ID) {
-		color = bg_color;
-	} else {
-#ifdef WORKBENCH_REVEALAGE_ENABLED
-		color = vec4((transparent_accum.xyz / max(transparent_accum.a, EPSILON)) * (1.0 - transparent_revealage), 1.0);
-		color = mix(bg_color, color, clamp(1.0 - transparent_revealage, 0.0, 1.0));
-#else
-		color = vec4(transparent_accum.xyz / max(transparent_accum.a, EPSILON), 1.0);
-#endif
-	}
-
-	fragColor = vec4(mix(world_data.object_outline_color.rgb, color.xyz, outline), 1.0);
+	vec3 bg_color = background_color(world_data, uv_viewport.y);
+
+	/* TODO: Bypass the whole shader if there is no xray pass and no outline pass. */
+	vec3 trans_color = trans_accum.rgb / clamp(trans_accum.a, 1e-4, 5e4);
+	vec3 color = mix(trans_color, bg_color, trans_revealage);
+
+	color = mix(world_data.object_outline_color.rgb, color, outline);
+
+	fragColor = vec4(color, 1.0);
 }
diff --git a/source/blender/draw/engines/workbench/shaders/workbench_forward_transparent_accum_frag.glsl b/source/blender/draw/engines/workbench/shaders/workbench_forward_transparent_accum_frag.glsl
index f1eacd281b1..53903a4af76 100644
--- a/source/blender/draw/engines/workbench/shaders/workbench_forward_transparent_accum_frag.glsl
+++ b/source/blender/draw/engines/workbench/shaders/workbench_forward_transparent_accum_frag.glsl
@@ -26,7 +26,7 @@ layout(std140) uniform material_block {
 };
 
 layout(location=0) out vec4 transparentAccum;
-
+layout(location=1) out float revealageAccum; /* revealage actually stored in transparentAccum.a */
 
 void main()
 {
@@ -70,7 +70,13 @@ void main()
 
 	vec3 shaded_color = diffuse_light * diffuse_color.rgb + specular_color;
 
-	vec4 premultiplied = vec4(shaded_color.rgb * alpha, alpha);
-	transparentAccum = calculate_transparent_accum(premultiplied);
+	/* Based on :
+	 * McGuire and Bavoil, Weighted Blended Order-Independent Transparency, Journal of
+	 * Computer Graphics Techniques (JCGT), vol. 2, no. 2, 122–141, 2013
+	 */
+	/* Listing 4 */
+	float weight = calculate_transparent_weight(alpha);
+	transparentAccum = vec4(shaded_color * weight, alpha);
+	revealageAccum = weight;
 }
 
diff --git a/source/blender/draw/engines/workbench/shaders/workbench_forward_transparent_revealage_frag.glsl b/source/blender/draw/engines/workbench/shaders/workbench_forward_transparent_revealage_frag.glsl
deleted file mode 100644
index c591425b950..00000000000
--- a/source/blender/draw/engines/workbench/shaders/workbench_forward_transparent_revealage_frag.glsl
+++ /dev/null
@@ -1,7 +0,0 @@
-layout(location=0) out float transparentRevealage;
-uniform float alpha = 0.5;
-void main()
-{
-	transparentRevealage = alpha;
-}
-
diff --git a/source/blender/draw/engines/workbench/workbench_forward.c b/source/blender/draw/engines/workbench/workbench_forward.c
index 3bc016e139b..8d67a936382 100644
--- a/source/blender/draw/engines/workbench/workbench_forward.c
+++ b/source/blender/draw/engines/workbench/workbench_forward.c
@@ -50,17 +50,13 @@
 static struct {
 	struct GPUShader *composite_sh_cache[MAX_SHADERS];
 	struct GPUShader *transparent_accum_sh_cache[MAX_SHADERS];
-	struct GPUShader *transparent_revealage_sh;
-	struct GPUShader *transparent_revealage_hair_sh;
 	struct GPUShader *object_outline_sh;
 	struct GPUShader *object_outline_hair_sh;
 	struct GPUShader *checker_depth_sh;
 
 	struct GPUTexture *object_id_tx; /* ref only, not alloced */
 	struct GPUTexture *transparent_accum_tx; /* ref only, not alloced */
-#ifdef WORKBENCH_REVEALAGE_ENABLED
 	struct GPUTexture *transparent_revealage_tx; /* ref only, not alloced */
-#endif
 	struct GPUTexture *composite_buffer_tx; /* ref only, not alloced */
 	int next_object_id;
 	float normal_world_matrix[3][3];
@@ -71,9 +67,6 @@ extern char datatoc_common_hair_lib_glsl[];
 extern char datatoc_workbench_forward_composite_frag_glsl[];
 extern char datatoc_workbench_forward_depth_frag_glsl[];
 extern char datatoc_workbench_forward_transparent_accum_frag_glsl[];
-#ifdef WORKBENCH_REVEALAGE_ENABLED
-extern char datatoc_workbench_forward_transparent_revealage_frag_glsl[];
-#endif
 extern char datatoc_workbench_data_lib_glsl[];
 extern char datatoc_workbench_background_lib_glsl[];
 extern char datatoc_workbench_checkerboard_depth_frag_glsl[];
@@ -127,22 +120,6 @@ static char *workbench_build_forward_transparent_accum_frag(void)
 	return str;
 }
 
-#ifdef WORKBENCH_REVEALAGE_ENABLED
-static char *workbench_build_forward_transparent_revealage_frag(void)
-{
-	char *str = NULL;
-
-	DynStr *ds = BLI_dynstr_new();
-
-	BLI_dynstr_append(ds, datatoc_workbench_common_lib_glsl);
-	BLI_dynstr_append(ds, datatoc_workbench_forward_transparent_revealage_frag_glsl);
-
-	str = BLI_dynstr_get_cstring(ds);
-	BLI_dynstr_free(ds);
-	return str;
-}
-#endif
-
 static char *workbench_build_forward_composite_frag(void)
 {
 	char *str = NULL;
@@ -310,17 +287,6 @@ void workbench_forward_engine_init(WORKBENCH_Data *vedata)
 		        forward_vert, NULL,
 		        forward_depth_frag, defines_hair);
 
-#ifdef WORKBENCH_REVEALAGE_ENABLED
-		char *forward_transparent_revealage_frag = workbench_build_forward_transparent_revealage_frag();
-		e_data.transparent_revealage_sh = DRW_shader_create(
-		        forward_vert, NULL,
-		        forward_transparent_revealage_frag, defines);
-		e_data.transparent_revealage_hair_sh = DRW_shader_create(
-		        forward_vert, NULL,
-		        forward_transparent_revealage_frag, defines_hair);
-		MEM_freeN(forward_transparent_revealage_frag);
-#endif
-
 		e_data.checker_depth_sh = DRW_shader_create_fullscreen(
 		        datatoc_workbench_checkerboard_depth_frag_glsl, NULL);
 		MEM_freeN(forward_vert);
@@ -337,63 +303,32 @@ void workbench_forward_engine_init(WORKBENCH_Data *vedata)
 	        size[0], size[1], GPU_R32UI, &draw_engine_workbench_transparent);
 	e_data.transparent_accum_tx = DRW_texture_pool_query_2D(
 	        size[0], size[1], GPU_RGBA16F, &draw_engine_workbench_transparent);
-#ifdef WORKBENCH_REVEALAGE_ENABLED
 	e_data.transparent_revealage_tx = DRW_texture_pool_query_2D(
 	        size[0], size[1], GPU_R16F, &draw_engine_workbench_transparent);
-#endif
 	e_data.composite_buffer_tx = DRW_texture_pool_query_2D(
 	        size[0], size[1], GPU_RGBA16F, &draw_engine_workbench_transparent);
+
 	GPU_framebuffer_ensure_config(&fbl->object_outline_fb, {
 		GPU_ATTACHMENT_TEXTURE(dtxl->depth),
 		GPU_ATTACHMENT_TEXTURE(e_data.object_id_tx),
 	});
+
 	GPU_framebuffer_ensure_config(&fbl->transparent_accum_fb, {
 		GPU_ATTACHMENT_NONE,
 		GPU_ATTACHMENT_TEXTURE(e_data.transparent_accum_tx),
-	});
-
-#ifdef WORKBENCH_REVEALAGE_ENABLED
-	GPU_framebuffer_ensure_config(&fbl->transparent_revealage_fb, {
-		GPU_ATTACHMENT_NONE,
 		GPU_ATTACHMENT_TEXTURE(e_data.transparent_revealage_tx),
 	});
-#endif
 
 	GPU_framebuffer_ensure_config(&fbl->composite_fb, {
 		GPU_ATTACHMENT_NONE,
 		GPU_ATTACHMENT_TEXTURE(e_data.composite_buffer_tx),
 	});
-	const float clear_color[4] = {0.0f, 0.0f, 0.0f, 0.0f};
-	DRW_stats_group_start("Clear Buffers");
-	GPU_framebuffer_bind(fbl->transparent_accum_fb);
-	GPU_framebuffer_clear_color(fbl->transparent_accum_fb, clear_color);
-
-#ifdef WORKBENCH_REVEALAGE_ENABLED
-	const float clear_color1[4] = {1.0f, 1.0f, 1.0f, 1.0f};
-	GPU_framebuffer_bind(fbl->transparent_revealage_fb);
-	GPU_framebuffer_clear_color(fbl->transparent_revealage_fb, clear_color1);
-#endif
-	GPU_framebuffer_bind(fbl->object_outline_fb);
-	GPU_framebuffer_clear_color_depth(fbl->object_outline_fb, clear_color, 1.0f);
-	DRW_stats_group_end();
 
 	/* Transparency Accum */
 	{
-		int state = DRW_STATE_WRITE_COLOR | DRW_STATE_ADDITIVE_FULL;
+		int state = DRW_STATE_WRITE_COLOR | DRW_STATE_BLEND_OIT;
 		psl->transparent_accum_pass = DRW_pass_create("Transparent Accum", state);
 	}
-
-#ifdef WORKBENCH_REVEALAGE_ENABLED
-	/* Transparency Revealage */
-	{
-		int state = DRW_STATE_WRITE_COLOR | DRW_STATE_TRANSPARENT_REVEALAGE;
-		psl->transparent_revealage_pass = DRW_pass_create("Transparent Revealage", state);
-		grp = DRW_shgroup_create(e_data.transparent_revealage_sh, psl->transparent_revealage_pass);
-		DRW_shgroup_uniform_float(grp, "alpha", &wpd->shading.xray_alpha, 1);
-		wpd->transparent_revealage_shgrp = grp;
-	}
-#endif
-
 	/* Depth */
 	{
 		int state = DRW_STATE_WRITE_COLOR | DRW_STATE_WRITE_DEPTH | DRW_STATE_DEPTH_LESS;
@@ -407,9 +342,7 @@ void workbench_forward_engine_init(WORKBENCH_Data *vedata)
 		grp = DRW_shgroup_create(wpd->composite_sh, psl->composite_pass);
 		DRW_shgroup_uniform_texture_ref(grp, "objectId", &e_data.object_id_tx);
 		DRW_shgroup_uniform_texture_ref(grp, "transparentAccum", &e_data.transparent_accum_tx);
-#ifdef WORKBENCH_REVEALAGE_ENABLED
 		DRW_shgroup_uniform_texture_ref(grp, "transparentRevealage", &e_data.transparent_revealage_tx);
-#endif
 		DRW_shgroup_uniform_block(grp, "world_block", wpd->world_ubo);
 		DRW_shgroup_uniform_vec2(grp, "invertedViewportSize", DRW_viewport_invert_size_get(), 1);
 		DRW_shgroup_call_add(grp, DRW_cache_fullscreen_quad_get(), NULL);
@@ -429,10 +362,6 @@ void workbench_forward_engine_free()
 		DRW_SHADER_FREE_SAFE(e_data.composite_sh_cache[index]);
 		DRW_SHADER_FREE_SAFE(e_data.transparent_accum_sh_cache[index]);
 	}
-#ifdef WORKBENCH_REVEALAGE_ENABLED
-	DRW_SHADER_FREE_SAFE(e_data.transparent_revealage_sh);
-	DRW_SHADER_FREE_SAFE(e_data.transparent_revealage_hair_sh);
-#endif
 	DRW_SHADER_FREE_SAFE(e_data.object_outline_sh);
 	DRW_SHADER_FREE_SAFE(e_data.object_outline_hair_sh);
 	DRW_SHADER_FREE_SAFE(e_data.checker_depth_sh);
@@ -496,12 +425,6 @@ static void workbench_forward_cache_populate_particles(WORKBENCH_Data *vedata, O
 				GPUTexture *tex = GPU_texture_from_blender(image, NULL, GL_TEXTURE_2D, false, false, false);
 				DRW_shgroup_uniform_texture(shgrp, "image", tex);
 			}
-#ifdef WORKBENCH_REVEALAGE_ENABLED
-			shgrp = DRW_shgroup_hair_create(ob, psys, md,
-			                        psl->transparent_revealage_pass,
-			                        e_data.transparent_revealage_hair_sh);
-			DRW_shgroup_uniform_float(shgrp, "alpha", &wpd->shading.xray_alpha, 1);
-#endif
 			shgrp = DRW_shgroup_hair_create(ob, psys, md,
 			                        vedata->psl->object_outline_pass,
 			                        e_data.object_outline_hair_sh);
@@ -550,9 +473,6 @@ void workbench_forward_cache_populate(WORKBENCH_Data *vedata, Object *ob)
 							mat_drawtype = OB_TEXTURE;
 						}
 						material = get_or_create_material_data(vedata, ob, mat, image, mat_drawtype);
-#ifdef WORKBENCH_REVEALAGE_ENABLED
-						DRW_shgroup_call_object_add(wpd->transparent_revealage_shgrp, geom_array[i], ob);
-#endif
 						DRW_shgroup_call_object_add(material->shgrp_object_outline, geom_array[i], ob);
 						DRW_shgroup_call_object_add(material->shgrp, geom_array[i], ob);
 					}
@@ -568,16 +488,10 @@ void workbench_forward_cache_populate(WORKBENCH_Data *vedata, Object *ob)
 				struct Gwn_Batch *geom = DRW_cache_object_surface_get(ob);
 				if (geom) {
 					if (is_sculpt_mode) {
-#ifdef WORKBENCH_REVEALAGE_ENABLED
-						DRW_shgroup_call_sculpt_add(wpd->transparent_revealage_shgrp, ob, ob->obmat);
-#endif
 						DRW_shgroup_call_sculpt_add(material->shgrp_object_outline, ob, ob->obmat);
 						DRW_shgroup_call_sculpt_add(material->shgrp, ob, ob->obmat);
 					}
 					else {
-#ifdef WORKBENCH_REVEALAGE_ENABLED
-						DRW_shgroup_call_object_add(wpd->transparent_revealage_shgrp, geom, ob);
-#endif
 						DRW_shgroup_call_object_add(material->shgrp_object_outline, geom, ob);
 						DRW_shgroup_call_object_add(material->shgrp, geom, ob);
 					}
@@ -596,9 +510,6 @@ void workbench_forward_cache_populate(WORKBENCH_Data *vedata, Object *ob)
 					for (int i = 0; i < materials_len; ++i) {
 						Material *mat = give_current_material(ob, i + 1);
 						material = get_or_create_material_data(vedata, ob, mat, NULL, OB_SOLID);
-#ifdef WORKBENCH_REVEALAGE_ENABLED
-						DRW_shgroup_call_object_add(wpd->transparent_revealage_shgrp, mat_geom[i], ob);
-#endif
 						DRW_shgroup_call_object_add(material->shgrp_object_outline, mat_geom[i], ob);
 						DRW_shgroup_call_object_add(material->shgrp, mat_geom[i], ob);
 					}
@@ -616,7 +527,7 @@ void workbench_forward_draw_background(WORKBENCH_Data *UNUSED(vedata))
 {
 	const float clear_depth = 1.0f;
 	DefaultFramebufferList *dfbl = DRW_viewport_framebuffer_list_get();
-	DRW_stats_group_start("Clear Background");
+	DRW_stats_group_start("Clear depth");
 	GPU_framebuffer_bind(dfbl->default_fb);
 	GPU_framebuffer_clear_depth(dfbl->default_fb, clear_depth);
 	DRW_stats_group_end();
@@ -631,17 +542,23 @@ void workbench_forward_draw_scene(WORKBENCH_Data *vedata)
 	DefaultFramebufferList *dfbl = DRW_viewport_framebuffer_list_get();
 
 	/* Write Depth + Object ID */
+	const float clear_outline[4] = {0.0f};
 	GPU_framebuffer_bind(fbl->object_outline_fb);
+	GPU_framebuffer_clear_color(fbl->object_outline_fb, clear_outline);
 	DRW_draw_pass(psl->object_outline_pass);
 
 	if (wpd->shading.xray_alpha > 0.0) {
-		/* Shade */
+		const float clear_color[4] = {0.0f, 0.0f, 0.0f, 1.0f};
 		GPU_framebuffer_bind(fbl->transparent_accum_fb);
+		GPU_framebuffer_clear_color(fbl->transparent_accum_fb, clear_color);
 		DRW_draw_pass(psl->transparent_accum_pass);
-#ifdef WORKBENCH_REVEALAGE_ENABLED
-		GPU_framebuffer_bind(fbl->transparent_revealage_fb);
-		DRW_draw_pass(psl->transparent_revealage_pass);
-#endif
+	}
+	else {
+		/* TODO(fclem): this is unecessary and takes up perf.
+		 * Better change the composite frag shader to not use the tx. */
+		const float clear_color[4] = {0.0f, 0.0f, 0.0f, 1.0f};
+		GPU_framebuffer_bind(fbl->transparent_accum_fb);
+		GPU_framebuffer_clear_color(fbl->transparent_accum_fb, clear_color);
 	}
 
 	/* Composite */
diff --git a/source/blender/draw/engines/workbench/workbench_materials.c b/source/blender/draw/engines/workbench/workbench_materials.c
index b25938cd0e5..231d9a9582a 100644
--- a/source/blender/draw/engines/workbench/workbench_materials.c
+++ b/source/blender/draw/engines/workbench/workbench_materials.c
@@ -95,10 +95,6 @@ char *workbench_material_build_defines(WORKBENCH_PrivateData *wpd, int drawtype,
 		BLI_dynstr_appendf(ds, "#define HAIR_SHADER\n");
 	}
 
-#ifdef WORKBENCH_REVEALAGE_ENABLED
-	BLI_dynstr_appendf(ds, "#define WORKBENCH_REVEALAGE_ENABLED\n");
-#endif
-
 	str = BLI_dynstr_get_cstring(ds);
 	BLI_dynstr_free(ds);
 	return str;
diff --git a/source/blender/draw/engines/workbench/workbench_private.h b/source/blender/draw/engines/workbench/workbench_private.h
index 9c5f97729bf..b17cc93d148 100644
--- a/source/blender/draw/engines/workbench/workbench_private.h
+++ b/source/blender/draw/engines/workbench/workbench_private.h
@@ -55,8 +55,6 @@
 #define NORMAL_VIEWPORT_COMP_PASS_ENABLED(wpd) (MATCAP_ENABLED(wpd) || STUDIOLIGHT_ENABLED(wpd) || SHADOW_ENABLED(wpd) || SPECULAR_HIGHLIGHT_ENABLED(wpd))
 #define NORMAL_VIEWPORT_PASS_ENABLED(wpd) (NORMAL_VIEWPORT_COMP_PASS_ENABLED(wpd) || CAVITY_ENABLED(wpd))
 #define NORMAL_ENCODING_ENABLED() (true)
-#define WORKBENCH_REVEALAGE_ENABLED
-
 
 typedef struct WORKBENCH_FramebufferList {
 	/* Deferred render buffers */
@@ -67,10 +65,7 @@ typedef struct WORKBENCH_FramebufferList {
 	/* Forward render buffers */
 	struct GPUFrameBuffer *object_outline_fb;
 	struct GPUFrameBuffer *transparent_accum_fb;
-
-#ifdef WORKBENCH_REVEALAGE_ENABLED
 	struct GPUFrameBuffer *transparent_revealage_fb;
-#endif
 } WORKBENCH_FramebufferList;
 
 typedef struct WORKBENCH_StorageList {
@@ -93,9 +88,6 @@ typedef struct WORKBENCH_PassList {
 
 	/* forward rendering */
 	struct DRWPass *transparent_accum_pass;
-#ifdef WORKBENCH_REVEALAGE_ENABLED
-	struct DRWPass *transparent_revealage_pass;
-#endif
 	struct DRWPass *object_outline_pass;
 	struct DRWPass *depth_pass;
 	struct DRWPass *checker_depth_pass;
@@ -158,9 +150,6 @@ typedef struct WORKBENCH_PrivateData {
 	struct GPUUniformBuffer *world_ubo;
 	struct DRWShadingGroup *shadow_shgrp;
 	struct DRWShadingGroup *depth_shgrp;
-#ifdef WORKBENCH_REVEALAGE_ENABLED
-	struct DRWShadingGroup *transparent_revealage_shgrp;
-#endif
 	WORKBENCH_UBO_World world_data;
 	float shadow_multiplier;
 	float cached_shadow_direction[3];
diff --git a/source/blender/draw/intern/DRW_render.h b/source/blender/draw/intern/DRW_render.h
index b74e6ba9204..f79a2405c3f 100644
--- a/source/blender/draw/intern/DRW_render.h
+++ b/source/blender/draw/intern/DRW_render.h
@@ -282,7 +282,7 @@ typedef enum {
 	DRW_STATE_BLEND_PREMUL  = (1 << 21), /* Use that if color is already premult by alpha. */
 	DRW_STATE_WIRE_SMOOTH   = (1 << 22),
 	DRW_STATE_TRANS_FEEDBACK = (1 << 23),
-	DRW_STATE_TRANSPARENT_REVEALAGE = (1 << 24),
+	DRW_STATE_BLEND_OIT     = (1 << 24),
 
 	DRW_STATE_WRITE_STENCIL          = (1 << 27),
 	DRW_STATE_WRITE_STENCIL_SHADOW_PASS   = (1 << 28),
diff --git a/source/blender/draw/intern/draw_manager_exec.c b/source/blender/draw/intern/draw_manager_exec.c
index f6b6438395d..3b7d19ac361 100644
--- a/source/blender/draw/intern/draw_manager_exec.c
+++ b/source/blender/draw/intern/draw_manager_exec.c
@@ -222,7 +222,7 @@ void drw_state_set(DRWState state)
 		if (CHANGED_ANY_STORE_VAR(
 		        DRW_STATE_BLEND | DRW_STATE_BLEND_PREMUL | DRW_STATE_ADDITIVE |
 		        DRW_STATE_MULTIPLY | DRW_STATE_TRANSMISSION | DRW_STATE_ADDITIVE_FULL |
-		        DRW_STATE_TRANSPARENT_REVEALAGE,
+		        DRW_STATE_BLEND_OIT,
 		        test))
 		{
 			if (test) {
@@ -241,8 +241,9 @@ void drw_state_set(DRWState state)
 				else if ((state & DRW_STATE_TRANSMISSION) != 0) {
 					glBlendFunc(GL_ONE, GL_SRC_ALPHA);
 				}
-				else if ((state & DRW_STATE_TRANSPARENT_REVEALAGE) != 0) {
-					glBlendFunc(GL_ZERO, GL_ONE_MINUS_SRC_COLOR);
+				else if ((state & DRW_STATE_BLEND_OIT) != 0) {
+					glBlendFuncSeparate(GL_ONE, GL_ONE, /* RGB */
+					                    GL_ZERO, GL_ONE_MINUS_SRC_ALPHA); /* Alpha */
 				}
 				else if ((state & DRW_STATE_ADDITIVE) != 0) {
 					/* Do not let alpha accumulate but premult the source RGB by it. */