Workbench: Specular Highlighting for MatCaps

With Blender 2.80 we introduced a more flexible matcap system. One
change we did was to multiply the matcap with the base color that was
shaded. As matcaps contains diffuse and specular lighting in a single
texture this lead to rendering artifacts. Artists were complaining that
everything looked to metalic.

We now support a separate `diffuse` and `specular` pass for matcaps.

`shaded_color = diffuse_light * base_color + specular_light`

For matcaps to support this feature they need to be multilayer openexr
files with 2 renderpasses (named `diffuse` and `specular`). In the future
we can change this to first pass/second pass in stead of this naming
convention.

Reviewed By: fclem, brecht

Differential Revision: https://developer.blender.org/D5335

6 files changed, 67 insertions, 26 deletions

diff --git a/source/blender/draw/engines/workbench/shaders/workbench_deferred_composite_frag.glsl b/source/blender/draw/engines/workbench/shaders/workbench_deferred_composite_frag.glsl
index a1f80440404..fd4cea4279a 100644
--- a/source/blender/draw/engines/workbench/shaders/workbench_deferred_composite_frag.glsl
+++ b/source/blender/draw/engines/workbench/shaders/workbench_deferred_composite_frag.glsl
@@ -5,7 +5,8 @@ uniform sampler2D materialBuffer;
 uniform sampler2D normalBuffer;
 /* normalBuffer contains viewport normals */
 uniform sampler2D cavityBuffer;
-uniform sampler2D matcapImage;
+uniform sampler2D matcapDiffuseImage;
+uniform sampler2D matcapSpecularImage;
 
 uniform vec2 invertedViewportSize;
 uniform vec4 viewvecs[3];
@@ -55,8 +56,15 @@ void main()
   normal_viewport = (metallic > 0.0) ? normal_viewport : -normal_viewport;
   bool flipped = world_data.matcap_orientation != 0;
   vec2 matcap_uv = matcap_uv_compute(I_vs, normal_viewport, flipped);
-  vec3 matcap = textureLod(matcapImage, matcap_uv, 0.0).rgb;
-  vec3 shaded_color = matcap * base_color;
+  vec3 matcap_diffuse = textureLod(matcapDiffuseImage, matcap_uv, 0.0).rgb;
+
+#  ifdef V3D_SHADING_SPECULAR_HIGHLIGHT
+  vec3 matcap_specular = textureLod(matcapSpecularImage, matcap_uv, 0.0).rgb;
+#  else
+  vec3 matcap_specular = vec3(0.0);
+#  endif
+
+  vec3 shaded_color = matcap_diffuse * base_color + matcap_specular;
 
 #elif defined(V3D_LIGHTING_STUDIO)
 
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 c78b2182d04..3333dfeff38 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
@@ -27,7 +27,8 @@ in vec2 uv_interp;
 in vec3 vertexColor;
 #endif
 #ifdef V3D_LIGHTING_MATCAP
-uniform sampler2D matcapImage;
+uniform sampler2D matcapDiffuseImage;
+uniform sampler2D matcapSpecularImage;
 #endif
 
 layout(std140) uniform world_block
@@ -68,8 +69,13 @@ void main()
 #elif defined(V3D_LIGHTING_MATCAP)
   bool flipped = world_data.matcap_orientation != 0;
   vec2 matcap_uv = matcap_uv_compute(I_vs, nor, flipped);
-  vec3 matcap = textureLod(matcapImage, matcap_uv, 0.0).rgb;
-  vec3 shaded_color = matcap * diffuse_color.rgb;
+  vec3 matcap_diffuse = textureLod(matcapDiffuseImage, matcap_uv, 0.0).rgb;
+#  ifdef V3D_SHADING_SPECULAR_HIGHLIGHT
+  vec3 matcap_specular = textureLod(matcapSpecularImage, matcap_uv, 0.0).rgb;
+#  else
+  vec3 matcap_specular = vec3(0.0);
+#  endif
+  vec3 shaded_color = matcap_diffuse * diffuse_color.rgb + matcap_specular;
 
 #elif defined(V3D_LIGHTING_STUDIO)
   vec3 shaded_color = get_world_lighting(
diff --git a/source/blender/draw/engines/workbench/workbench_deferred.c b/source/blender/draw/engines/workbench/workbench_deferred.c
index add49462de1..c1c9d8b5a96 100644
--- a/source/blender/draw/engines/workbench/workbench_deferred.c
+++ b/source/blender/draw/engines/workbench/workbench_deferred.c
@@ -694,16 +694,22 @@ static void workbench_composite_uniforms(WORKBENCH_PrivateData *wpd, DRWShadingG
   if (CAVITY_ENABLED(wpd)) {
     DRW_shgroup_uniform_texture_ref(grp, "cavityBuffer", &e_data.cavity_buffer_tx);
   }
-  if (SPECULAR_HIGHLIGHT_ENABLED(wpd) || STUDIOLIGHT_TYPE_MATCAP_ENABLED(wpd)) {
+  if (workbench_is_specular_highlight_enabled(wpd) || STUDIOLIGHT_TYPE_MATCAP_ENABLED(wpd)) {
     DRW_shgroup_uniform_vec4(grp, "viewvecs[0]", (float *)wpd->viewvecs, 3);
   }
-  if (SPECULAR_HIGHLIGHT_ENABLED(wpd) || STUDIOLIGHT_TYPE_MATCAP_ENABLED(wpd)) {
+  if (workbench_is_specular_highlight_enabled(wpd) || STUDIOLIGHT_TYPE_MATCAP_ENABLED(wpd)) {
     DRW_shgroup_uniform_vec2(grp, "invertedViewportSize", DRW_viewport_invert_size_get(), 1);
   }
   if (STUDIOLIGHT_TYPE_MATCAP_ENABLED(wpd)) {
-    BKE_studiolight_ensure_flag(wpd->studio_light, STUDIOLIGHT_EQUIRECT_RADIANCE_GPUTEXTURE);
+    BKE_studiolight_ensure_flag(wpd->studio_light,
+                                STUDIOLIGHT_MATCAP_DIFFUSE_GPUTEXTURE |
+                                    STUDIOLIGHT_MATCAP_SPECULAR_GPUTEXTURE);
     DRW_shgroup_uniform_texture(
-        grp, "matcapImage", wpd->studio_light->equirect_radiance_gputexture);
+        grp, "matcapDiffuseImage", wpd->studio_light->matcap_diffuse.gputexture);
+    if (workbench_is_specular_highlight_enabled(wpd)) {
+      DRW_shgroup_uniform_texture(
+          grp, "matcapSpecularImage", wpd->studio_light->matcap_specular.gputexture);
+    }
   }
 }
 
diff --git a/source/blender/draw/engines/workbench/workbench_forward.c b/source/blender/draw/engines/workbench/workbench_forward.c
index 4c1fce550e8..824c6e7bd76 100644
--- a/source/blender/draw/engines/workbench/workbench_forward.c
+++ b/source/blender/draw/engines/workbench/workbench_forward.c
@@ -186,11 +186,17 @@ WORKBENCH_MaterialData *workbench_forward_get_or_create_material_data(WORKBENCH_
     DRW_shgroup_uniform_vec4(grp, "viewvecs[0]", (float *)wpd->viewvecs, 3);
     workbench_material_copy(material, &material_template);
     if (STUDIOLIGHT_TYPE_MATCAP_ENABLED(wpd)) {
-      BKE_studiolight_ensure_flag(wpd->studio_light, STUDIOLIGHT_EQUIRECT_RADIANCE_GPUTEXTURE);
+      BKE_studiolight_ensure_flag(wpd->studio_light,
+                                  STUDIOLIGHT_MATCAP_DIFFUSE_GPUTEXTURE |
+                                      STUDIOLIGHT_MATCAP_SPECULAR_GPUTEXTURE);
       DRW_shgroup_uniform_texture(
-          grp, "matcapImage", wpd->studio_light->equirect_radiance_gputexture);
+          grp, "matcapDiffuseImage", wpd->studio_light->matcap_diffuse.gputexture);
+      if (workbench_is_specular_highlight_enabled(wpd)) {
+        DRW_shgroup_uniform_texture(
+            grp, "matcapSpecularImage", wpd->studio_light->matcap_specular.gputexture);
+      }
     }
-    if (SPECULAR_HIGHLIGHT_ENABLED(wpd) || MATCAP_ENABLED(wpd)) {
+    if (workbench_is_specular_highlight_enabled(wpd) || MATCAP_ENABLED(wpd)) {
       DRW_shgroup_uniform_vec2(grp, "invertedViewportSize", DRW_viewport_invert_size_get(), 1);
     }
     if (SHADOW_ENABLED(wpd)) {
@@ -528,11 +534,17 @@ static void workbench_forward_cache_populate_particles(WORKBENCH_Data *vedata, O
       float hair_alpha = XRAY_ALPHA(wpd) * 0.33f;
       DRW_shgroup_uniform_float_copy(shgrp, "alpha", hair_alpha);
       if (STUDIOLIGHT_TYPE_MATCAP_ENABLED(wpd)) {
-        BKE_studiolight_ensure_flag(wpd->studio_light, STUDIOLIGHT_EQUIRECT_RADIANCE_GPUTEXTURE);
+        BKE_studiolight_ensure_flag(wpd->studio_light,
+                                    STUDIOLIGHT_MATCAP_DIFFUSE_GPUTEXTURE |
+                                        STUDIOLIGHT_MATCAP_SPECULAR_GPUTEXTURE);
         DRW_shgroup_uniform_texture(
-            shgrp, "matcapImage", wpd->studio_light->equirect_radiance_gputexture);
+            shgrp, "matcapDiffuseImage", wpd->studio_light->matcap_diffuse.gputexture);
+        if (workbench_is_specular_highlight_enabled(wpd)) {
+          DRW_shgroup_uniform_texture(
+              shgrp, "matcapSpecularImage", wpd->studio_light->matcap_specular.gputexture);
+        }
       }
-      if (SPECULAR_HIGHLIGHT_ENABLED(wpd) || MATCAP_ENABLED(wpd)) {
+      if (workbench_is_specular_highlight_enabled(wpd) || MATCAP_ENABLED(wpd)) {
         DRW_shgroup_uniform_vec2(shgrp, "invertedViewportSize", DRW_viewport_invert_size_get(), 1);
       }
 
diff --git a/source/blender/draw/engines/workbench/workbench_materials.c b/source/blender/draw/engines/workbench/workbench_materials.c
index 6699a1954ba..e050877187e 100644
--- a/source/blender/draw/engines/workbench/workbench_materials.c
+++ b/source/blender/draw/engines/workbench/workbench_materials.c
@@ -79,7 +79,7 @@ void workbench_material_update_data(WORKBENCH_PrivateData *wpd,
     /* V3D_SHADING_MATERIAL_COLOR or V3D_SHADING_TEXTURE_COLOR */
     if (mat) {
       data->alpha *= mat->a;
-      if (SPECULAR_HIGHLIGHT_ENABLED(wpd)) {
+      if (workbench_is_specular_highlight_enabled(wpd)) {
         copy_v3_v3(data->base_color, &mat->r);
         mul_v3_v3fl(data->diffuse_color, &mat->r, 1.0f - mat->metallic);
         mul_v3_v3fl(data->specular_color, &mat->r, mat->metallic);
@@ -121,7 +121,7 @@ char *workbench_material_build_defines(WORKBENCH_PrivateData *wpd,
   if (SSAO_ENABLED(wpd) || CURVATURE_ENABLED(wpd)) {
     BLI_dynstr_append(ds, "#define WB_CAVITY\n");
   }
-  if (SPECULAR_HIGHLIGHT_ENABLED(wpd)) {
+  if (workbench_is_specular_highlight_enabled(wpd)) {
     BLI_dynstr_append(ds, "#define V3D_SHADING_SPECULAR_HIGHLIGHT\n");
   }
   if (STUDIOLIGHT_ENABLED(wpd)) {
@@ -195,11 +195,12 @@ int workbench_material_get_composite_shader_index(WORKBENCH_PrivateData *wpd)
   /* NOTE: change MAX_COMPOSITE_SHADERS accordingly when modifying this function. */
   int index = 0;
   /* 2 bits FLAT/STUDIO/MATCAP + Specular highlight */
-  index = SPECULAR_HIGHLIGHT_ENABLED(wpd) ? 3 : wpd->shading.light;
+  index = wpd->shading.light;
   SET_FLAG_FROM_TEST(index, wpd->shading.flag & V3D_SHADING_SHADOW, 1 << 2);
   SET_FLAG_FROM_TEST(index, wpd->shading.flag & V3D_SHADING_CAVITY, 1 << 3);
   SET_FLAG_FROM_TEST(index, wpd->shading.flag & V3D_SHADING_OBJECT_OUTLINE, 1 << 4);
   SET_FLAG_FROM_TEST(index, workbench_is_matdata_pass_enabled(wpd), 1 << 5);
+  SET_FLAG_FROM_TEST(index, workbench_is_specular_highlight_enabled(wpd), 1 << 6);
   BLI_assert(index < MAX_COMPOSITE_SHADERS);
   return index;
 }
@@ -246,12 +247,13 @@ int workbench_material_get_accum_shader_index(WORKBENCH_PrivateData *wpd,
   /* NOTE: change MAX_ACCUM_SHADERS accordingly when modifying this function. */
   int index = 0;
   /* 2 bits FLAT/STUDIO/MATCAP + Specular highlight */
-  index = SPECULAR_HIGHLIGHT_ENABLED(wpd) ? 3 : wpd->shading.light;
+  index = wpd->shading.light;
   SET_FLAG_FROM_TEST(index, use_textures, 1 << 2);
   SET_FLAG_FROM_TEST(index, use_vertex_colors, 1 << 3);
   SET_FLAG_FROM_TEST(index, is_hair, 1 << 4);
   /* 1 bits SHADOWS (only facing factor) */
   SET_FLAG_FROM_TEST(index, SHADOW_ENABLED(wpd), 1 << 5);
+  SET_FLAG_FROM_TEST(index, workbench_is_specular_highlight_enabled(wpd), 1 << 6);
   BLI_assert(index < MAX_ACCUM_SHADERS);
   return index;
 }
@@ -333,7 +335,7 @@ void workbench_material_shgroup_uniform(WORKBENCH_PrivateData *wpd,
                                1);
     }
 
-    if (SPECULAR_HIGHLIGHT_ENABLED(wpd)) {
+    if (workbench_is_specular_highlight_enabled(wpd)) {
       if (use_metallic) {
         DRW_shgroup_uniform_float(grp, "materialMetallic", &material->metallic, 1);
       }
diff --git a/source/blender/draw/engines/workbench/workbench_private.h b/source/blender/draw/engines/workbench/workbench_private.h
index 255b036eebb..d880d5d58b5 100644
--- a/source/blender/draw/engines/workbench/workbench_private.h
+++ b/source/blender/draw/engines/workbench/workbench_private.h
@@ -36,9 +36,9 @@
 
 #define WORKBENCH_ENGINE "BLENDER_WORKBENCH"
 #define M_GOLDEN_RATION_CONJUGATE 0.618033988749895
-#define MAX_COMPOSITE_SHADERS (1 << 6)
+#define MAX_COMPOSITE_SHADERS (1 << 7)
 #define MAX_PREPASS_SHADERS (1 << 7)
-#define MAX_ACCUM_SHADERS (1 << 6)
+#define MAX_ACCUM_SHADERS (1 << 7)
 #define MAX_CAVITY_SHADERS (1 << 3)
 
 #define TEXTURE_DRAWING_ENABLED(wpd) (wpd->shading.color_type == V3D_SHADING_TEXTURE_COLOR)
@@ -77,9 +77,6 @@
 #define IS_NAVIGATING(wpd) \
   ((DRW_context_state_get()->rv3d) && (DRW_context_state_get()->rv3d->rflag & RV3D_NAVIGATING))
 
-#define SPECULAR_HIGHLIGHT_ENABLED(wpd) \
-  (STUDIOLIGHT_ENABLED(wpd) && (wpd->shading.flag & V3D_SHADING_SPECULAR_HIGHLIGHT) && \
-   (!STUDIOLIGHT_TYPE_MATCAP_ENABLED(wpd)))
 #define OBJECT_OUTLINE_ENABLED(wpd) (wpd->shading.flag & V3D_SHADING_OBJECT_OUTLINE)
 #define OBJECT_ID_PASS_ENABLED(wpd) (OBJECT_OUTLINE_ENABLED(wpd) || CURVATURE_ENABLED(wpd))
 #define NORMAL_VIEWPORT_COMP_PASS_ENABLED(wpd) \
@@ -316,6 +313,16 @@ typedef struct WORKBENCH_ObjectData {
 } WORKBENCH_ObjectData;
 
 /* inline helper functions */
+BLI_INLINE bool workbench_is_specular_highlight_enabled(WORKBENCH_PrivateData *wpd)
+{
+  if ((wpd->shading.flag & V3D_SHADING_SPECULAR_HIGHLIGHT)) {
+    if (STUDIOLIGHT_ENABLED(wpd) || MATCAP_ENABLED(wpd)) {
+      return (wpd->studio_light->flag & STUDIOLIGHT_SPECULAR_HIGHLIGHT_PASS) != 0;
+    }
+  }
+  return false;
+}
+
 BLI_INLINE bool workbench_is_taa_enabled(WORKBENCH_PrivateData *wpd)
 {
   if (DRW_state_is_image_render()) {