Object Mode: Outlines: Add support for thicker outline

Base outline is 2px wide (because of how we detect them).
And since inflating this outline will only produce outlines that are 2*x
thick we map the UI scalling and the outline width setting to the closest
match.

Do note that thicker outlines have a performance cost since they need more
texture fetches and passes.

This fixes T60252 3D View Outline Width not working

2 files changed, 26 insertions, 8 deletions

diff --git a/source/blender/draw/modes/object_mode.c b/source/blender/draw/modes/object_mode.c
index 63273229096..0f69e248409 100644
--- a/source/blender/draw/modes/object_mode.c
+++ b/source/blender/draw/modes/object_mode.c
@@ -314,6 +314,7 @@ static struct {
 	GPUShader *outline_detect_sh;
 	GPUShader *outline_detect_wire_sh;
 	GPUShader *outline_fade_sh;
+	GPUShader *outline_fade_large_sh;
 
 	/* regular shaders */
 	GPUShader *object_empty_image_sh;
@@ -435,6 +436,7 @@ static void OBJECT_engine_init(void *vedata)
 
 
 		e_data.outline_fade_sh = DRW_shader_create_fullscreen(datatoc_object_outline_expand_frag_glsl, NULL);
+		e_data.outline_fade_large_sh = DRW_shader_create_fullscreen(datatoc_object_outline_expand_frag_glsl, "#define LARGE_OUTLINE\n");
 
 		/* Empty images */
 #		define EMPTY_IMAGE_SHADER_DEFINES \
@@ -670,6 +672,7 @@ static void OBJECT_engine_free(void)
 	DRW_SHADER_FREE_SAFE(e_data.outline_detect_sh);
 	DRW_SHADER_FREE_SAFE(e_data.outline_detect_wire_sh);
 	DRW_SHADER_FREE_SAFE(e_data.outline_fade_sh);
+	DRW_SHADER_FREE_SAFE(e_data.outline_fade_large_sh);
 	DRW_SHADER_FREE_SAFE(e_data.object_empty_image_sh);
 	DRW_SHADER_FREE_SAFE(e_data.object_empty_image_wire_sh);
 	DRW_SHADER_FREE_SAFE(e_data.grid_sh);
@@ -985,8 +988,10 @@ static void OBJECT_cache_init(void *vedata)
 	DefaultTextureList *dtxl = DRW_viewport_texture_list_get();
 	OBJECT_PrivateData *g_data;
 	const DRWContextState *draw_ctx = DRW_context_state_get();
-	/* TODO : use dpi setting for enabling the second pass */
-	const bool do_outline_expand = false;
+
+	const float outline_width = UI_GetThemeValuef(TH_OUTLINE_WIDTH);
+	const bool do_outline_expand = (U.pixelsize > 1.0) || (outline_width > 2.0f);
+	const bool do_large_expand = ((U.pixelsize > 1.0) && (outline_width > 2.0f)) || (outline_width > 4.0f);
 
 	if (!stl->g_data) {
 		/* Alloc transient pointers */
@@ -1046,9 +1051,6 @@ static void OBJECT_cache_init(void *vedata)
 		struct GPUBatch *quad = DRW_cache_fullscreen_quad_get();
 		/* Don't occlude the "outline" detection pass if in xray mode (too much flickering). */
 		float alphaOcclu = (g_data->xray_enabled) ? 1.0f : 0.35f;
-		/* Reminder : bool uniforms need to be 4 bytes. */
-		static const int bTrue = true;
-		static const int bFalse = false;
 
 		psl->outlines_search = DRW_pass_create("Outlines Detect Pass", state);
 
@@ -1062,11 +1064,13 @@ static void OBJECT_cache_init(void *vedata)
 		DRW_shgroup_uniform_int(grp, "idOffsets", &stl->g_data->id_ofs_active, 4);
 		DRW_shgroup_call_add(grp, quad, NULL);
 
+		/* This is the bleed pass if do_outline_expand is false. */
+		GPUShader *fade_sh = (do_large_expand) ? e_data.outline_fade_large_sh : e_data.outline_fade_sh;
 		psl->outlines_expand = DRW_pass_create("Outlines Expand Pass", state);
 
-		grp = DRW_shgroup_create(e_data.outline_fade_sh, psl->outlines_expand);
+		grp = DRW_shgroup_create(fade_sh, psl->outlines_expand);
 		DRW_shgroup_uniform_texture_ref(grp, "outlineColor", &e_data.outlines_blur_tx);
-		DRW_shgroup_uniform_bool(grp, "doExpand", (do_outline_expand) ? &bTrue : &bFalse, 1);
+		DRW_shgroup_uniform_bool_copy(grp, "doExpand", do_outline_expand);
 		DRW_shgroup_call_add(grp, quad, NULL);
 
 		psl->outlines_bleed = DRW_pass_create("Outlines Bleed Pass", state);
@@ -1074,7 +1078,7 @@ static void OBJECT_cache_init(void *vedata)
 		if (do_outline_expand) {
 			grp = DRW_shgroup_create(e_data.outline_fade_sh, psl->outlines_bleed);
 			DRW_shgroup_uniform_texture_ref(grp, "outlineColor", &e_data.outlines_color_tx);
-			DRW_shgroup_uniform_bool(grp, "doExpand", &bFalse, 1);
+			DRW_shgroup_uniform_bool_copy(grp, "doExpand", false);
 			DRW_shgroup_call_add(grp, quad, NULL);
 		}
 	}
diff --git a/source/blender/draw/modes/shaders/object_outline_expand_frag.glsl b/source/blender/draw/modes/shaders/object_outline_expand_frag.glsl
index 7e288cde236..8b5603919c4 100644
--- a/source/blender/draw/modes/shaders/object_outline_expand_frag.glsl
+++ b/source/blender/draw/modes/shaders/object_outline_expand_frag.glsl
@@ -28,6 +28,20 @@ void main()
 		return;
 	}
 
+#ifdef LARGE_OUTLINE
+	if (!any(btests)) {
+		color[0] = texelFetchOffset(outlineColor, uv, 0, ivec2( 2,  0)).rgba;
+		color[1] = texelFetchOffset(outlineColor, uv, 0, ivec2( 0,  2)).rgba;
+		color[2] = texelFetchOffset(outlineColor, uv, 0, ivec2(-2,  0)).rgba;
+		color[3] = texelFetchOffset(outlineColor, uv, 0, ivec2( 0, -2)).rgba;
+
+		values = vec4(color[0].a, color[1].a, color[2].a, color[3].a);
+
+		tests = step(vec4(1e-6), values); /* (color.a != 0.0) */
+		btests = equal(tests, vec4(1.0));
+	}
+#endif
+
 	FragColor = (btests.x) ? color[0] : FragColor;
 	FragColor = (btests.y) ? color[1] : FragColor;
 	FragColor = (btests.z) ? color[2] : FragColor;