Vertex Paint: Use Linear colors for interpolation.

This matches Cycles and Eevee's behaviour.

4 files changed, 45 insertions, 12 deletions

diff --git a/source/blender/draw/CMakeLists.txt b/source/blender/draw/CMakeLists.txt
index 6ee2acecbb4..cffd135369a 100644
--- a/source/blender/draw/CMakeLists.txt
+++ b/source/blender/draw/CMakeLists.txt
@@ -254,6 +254,8 @@ data_to_c_simple(modes/shaders/object_particle_dot_vert.glsl SRC)
 data_to_c_simple(modes/shaders/object_particle_dot_frag.glsl SRC)
 data_to_c_simple(modes/shaders/paint_texture_frag.glsl SRC)
 data_to_c_simple(modes/shaders/paint_texture_vert.glsl SRC)
+data_to_c_simple(modes/shaders/paint_vertex_frag.glsl SRC)
+data_to_c_simple(modes/shaders/paint_vertex_vert.glsl SRC)
 data_to_c_simple(modes/shaders/paint_wire_frag.glsl SRC)
 data_to_c_simple(modes/shaders/paint_wire_vert.glsl SRC)
 data_to_c_simple(modes/shaders/paint_vert_frag.glsl SRC)
diff --git a/source/blender/draw/modes/paint_vertex_mode.c b/source/blender/draw/modes/paint_vertex_mode.c
index 2c963571302..a48effa4bfc 100644
--- a/source/blender/draw/modes/paint_vertex_mode.c
+++ b/source/blender/draw/modes/paint_vertex_mode.c
@@ -38,6 +38,8 @@
 extern struct GPUUniformBuffer *globals_ubo; /* draw_common.c */
 extern struct GlobalsUboStorage ts; /* draw_common.c */
 
+extern char datatoc_paint_vertex_vert_glsl[];
+extern char datatoc_paint_vertex_frag_glsl[];
 extern char datatoc_paint_wire_vert_glsl[];
 extern char datatoc_paint_wire_frag_glsl[];
 extern char datatoc_common_globals_lib_glsl[];
@@ -81,17 +83,15 @@ typedef struct PAINT_VERTEX_PrivateData {
 static void PAINT_VERTEX_engine_init(void *UNUSED(vedata))
 {
 	if (!e_data.vcolor_face_shader) {
-		e_data.vcolor_face_shader = GPU_shader_get_builtin_shader(GPU_SHADER_SIMPLE_LIGHTING_SMOOTH_COLOR_ALPHA);
-	}
+		e_data.vcolor_face_shader = DRW_shader_create(
+		        datatoc_paint_vertex_vert_glsl, NULL,
+		        datatoc_paint_vertex_frag_glsl, NULL);
 
-	if (!e_data.wire_overlay_shader) {
 		e_data.wire_overlay_shader = DRW_shader_create_with_lib(
 		        datatoc_paint_wire_vert_glsl, NULL,
 		        datatoc_paint_wire_frag_glsl,
 		        datatoc_common_globals_lib_glsl, "#define VERTEX_MODE\n");
-	}
 
-	if (!e_data.face_overlay_shader) {
 		e_data.face_overlay_shader = GPU_shader_get_builtin_shader(GPU_SHADER_3D_UNIFORM_COLOR);
 	}
 }
@@ -113,13 +113,6 @@ static void PAINT_VERTEX_cache_init(void *vedata)
 		        DRW_STATE_WRITE_COLOR | DRW_STATE_WRITE_DEPTH | DRW_STATE_DEPTH_LESS | DRW_STATE_MULTIPLY);
 
 		stl->g_data->fvcolor_shgrp = DRW_shgroup_create(e_data.vcolor_face_shader, psl->vcolor_faces);
-
-		static float light[3] = {-0.3f, 0.5f, 1.0f};
-		static float alpha = 1.0f;
-		static float world_light = 1.0f;
-		DRW_shgroup_uniform_vec3(stl->g_data->fvcolor_shgrp, "light", light, 1);
-		DRW_shgroup_uniform_float(stl->g_data->fvcolor_shgrp, "alpha", &alpha, 1);
-		DRW_shgroup_uniform_float(stl->g_data->fvcolor_shgrp, "global", &world_light, 1);
 	}
 
 	{
diff --git a/source/blender/draw/modes/shaders/paint_vertex_frag.glsl b/source/blender/draw/modes/shaders/paint_vertex_frag.glsl
new file mode 100644
index 00000000000..5a00fec9c43
--- /dev/null
+++ b/source/blender/draw/modes/shaders/paint_vertex_frag.glsl
@@ -0,0 +1,17 @@
+
+in vec3 finalColor;
+
+out vec4 fragColor;
+
+vec3 linear_to_srgb_attrib(vec3 c) {
+	c = max(c, vec3(0.0));
+	vec3 c1 = c * 12.92;
+	vec3 c2 = 1.055 * pow(c, vec3(1.0 / 2.4)) - 0.055;
+	return mix(c1, c2, step(vec3(0.0031308), c));
+}
+
+void main()
+{
+	fragColor.rgb = linear_to_srgb_attrib(finalColor);
+	fragColor.a = 1.0;
+}
diff --git a/source/blender/draw/modes/shaders/paint_vertex_vert.glsl b/source/blender/draw/modes/shaders/paint_vertex_vert.glsl
new file mode 100644
index 00000000000..178f77c6b9c
--- /dev/null
+++ b/source/blender/draw/modes/shaders/paint_vertex_vert.glsl
@@ -0,0 +1,21 @@
+
+uniform mat4 ModelViewProjectionMatrix;
+
+in vec3 pos;
+in vec3 color;
+
+out vec3 finalColor;
+
+vec3 srgb_to_linear_attrib(vec3 c) {
+	c = max(c, vec3(0.0));
+	vec3 c1 = c * (1.0 / 12.92);
+	vec3 c2 = pow((c + 0.055) * (1.0 / 1.055), vec3(2.4));
+	return mix(c1, c2, step(vec3(0.04045), c));
+}
+
+void main()
+{
+	gl_Position = ModelViewProjectionMatrix * vec4(pos, 1.0);
+
+	finalColor = srgb_to_linear_attrib(color);
+}