BLF: Opti: Draw only one quad per shadow/blurred glyph.

This port the Blurring of blf fonts to the final drawing shader.

We add a bit of extra padding to each glyph so that jittering the texture
coord does not sample the neighbor glyphs.

3 files changed, 97 insertions, 9 deletions

diff --git a/source/blender/gpu/shaders/gpu_shader_text_frag.glsl b/source/blender/gpu/shaders/gpu_shader_text_frag.glsl
index 7ff90ad4f21..3e5fdd8b90b 100644
--- a/source/blender/gpu/shaders/gpu_shader_text_frag.glsl
+++ b/source/blender/gpu/shaders/gpu_shader_text_frag.glsl
@@ -1,15 +1,99 @@
 
 flat in vec4 color_flat;
+flat in vec4 texCoord_rect;
 noperspective in vec2 texCoord_interp;
 out vec4 fragColor;
 
 uniform sampler2D glyph;
 
+const vec2 offsets9[9] = vec2[9](
+	vec2(-1.0, -1.0), vec2( 0.0, -1.0), vec2( 1.0, -1.0),
+	vec2(-1.0,  0.0), vec2( 0.0,  0.0), vec2( 1.0,  0.0),
+	vec2(-1.0,  1.0), vec2( 0.0,  1.0), vec2( 1.0,  1.0)
+);
+
+const vec2 offsets25[25] = vec2[25](
+	vec2(-2.0, -2.0), vec2(-1.0, -2.0), vec2( 0.0, -2.0), vec2( 1.0, -2.0), vec2( 2.0, -2.0),
+	vec2(-2.0, -1.0), vec2(-1.0, -1.0), vec2( 0.0, -1.0), vec2( 1.0, -1.0), vec2( 2.0, -1.0),
+	vec2(-2.0,  0.0), vec2(-1.0,  0.0), vec2( 0.0,  0.0), vec2( 1.0,  0.0), vec2( 2.0,  0.0),
+	vec2(-2.0,  1.0), vec2(-1.0,  1.0), vec2( 0.0,  1.0), vec2( 1.0,  1.0), vec2( 2.0,  1.0),
+	vec2(-2.0,  2.0), vec2(-1.0,  2.0), vec2( 0.0,  2.0), vec2( 1.0,  2.0), vec2( 2.0,  2.0)
+);
+
+const float weights9[9] = float[9](
+	1.0 / 16.0, 2.0 / 16.0, 1.0 / 16.0,
+	2.0 / 16.0, 4.0 / 16.0, 2.0 / 16.0,
+	1.0 / 16.0, 2.0 / 16.0, 1.0 / 16.0
+);
+
+const float weights25[25] = float[25](
+	1.0 / 60.0, 1.0 / 60.0, 2.0 / 60.0, 1.0 / 60.0, 1.0 / 60.0,
+	1.0 / 60.0, 3.0 / 60.0, 5.0 / 60.0, 3.0 / 60.0, 1.0 / 60.0,
+	2.0 / 60.0, 5.0 / 60.0, 8.0 / 60.0, 5.0 / 60.0, 2.0 / 60.0,
+	1.0 / 60.0, 3.0 / 60.0, 5.0 / 60.0, 3.0 / 60.0, 1.0 / 60.0,
+	1.0 / 60.0, 1.0 / 60.0, 2.0 / 60.0, 1.0 / 60.0, 1.0 / 60.0
+);
+
+#define sample_glyph_offset(texco, texel, ofs) texture(glyph, texco + ofs * texel).r
+
 void main()
 {
 	// input color replaces texture color
 	fragColor.rgb = color_flat.rgb;
 
+	vec2 texel = 1.0 / vec2(textureSize(glyph, 0));
+	vec2 texco = mix(abs(texCoord_rect.xy), abs(texCoord_rect.zw), texCoord_interp);
+
 	// modulate input alpha & texture alpha
-	fragColor.a = color_flat.a * texture(glyph, texCoord_interp).r;
+	if (texCoord_rect.x > 0) {
+		fragColor.a = texture(glyph, texco).r;
+	}
+	else {
+		fragColor.a = 0.0;
+
+		if (texCoord_rect.w > 0) {
+			/* 3x3 blur */
+			/* Manual unroll for perf. (stupid glsl compiler) */
+			fragColor.a += sample_glyph_offset(texco, texel, offsets9[0]) * weights9[0];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets9[1]) * weights9[1];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets9[2]) * weights9[2];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets9[3]) * weights9[3];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets9[4]) * weights9[4];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets9[5]) * weights9[5];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets9[6]) * weights9[6];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets9[7]) * weights9[7];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets9[8]) * weights9[8];
+		}
+		else {
+			/* 5x5 blur */
+			/* Manual unroll for perf. (stupid glsl compiler) */
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[ 0]) * weights25[ 0];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[ 1]) * weights25[ 1];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[ 2]) * weights25[ 2];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[ 3]) * weights25[ 3];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[ 4]) * weights25[ 4];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[ 5]) * weights25[ 5];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[ 6]) * weights25[ 6];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[ 7]) * weights25[ 7];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[ 8]) * weights25[ 8];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[ 9]) * weights25[ 9];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[10]) * weights25[10];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[11]) * weights25[11];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[12]) * weights25[12];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[13]) * weights25[13];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[14]) * weights25[14];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[15]) * weights25[15];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[16]) * weights25[16];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[17]) * weights25[17];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[18]) * weights25[18];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[19]) * weights25[19];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[20]) * weights25[20];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[21]) * weights25[21];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[22]) * weights25[22];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[23]) * weights25[23];
+			fragColor.a += sample_glyph_offset(texco, texel, offsets25[24]) * weights25[24];
+		}
+	}
+
+	fragColor.a *= color_flat.a;
 }
diff --git a/source/blender/gpu/shaders/gpu_shader_text_geom.glsl b/source/blender/gpu/shaders/gpu_shader_text_geom.glsl
index d4d86db6bc3..0acd2106f7a 100644
--- a/source/blender/gpu/shaders/gpu_shader_text_geom.glsl
+++ b/source/blender/gpu/shaders/gpu_shader_text_geom.glsl
@@ -9,26 +9,28 @@ in vec4 tex_rect[];
 in vec4 color[];
 
 flat out vec4 color_flat;
+flat out vec4 texCoord_rect;
 noperspective out vec2 texCoord_interp;
 
 void main()
 {
 	color_flat = color[0];
+	texCoord_rect = tex_rect[0];
 
 	gl_Position = (ModelViewProjectionMatrix * vec4(pos_rect[0].xy, 0.0, 1.0));
-	texCoord_interp = tex_rect[0].xy;
+	texCoord_interp = vec2(0.0, 0.0);
 	EmitVertex();
 
 	gl_Position = (ModelViewProjectionMatrix * vec4(pos_rect[0].zy, 0.0, 1.0));
-	texCoord_interp = tex_rect[0].zy;
+	texCoord_interp = vec2(1.0, 0.0);
 	EmitVertex();
 
 	gl_Position = (ModelViewProjectionMatrix * vec4(pos_rect[0].xw, 0.0, 1.0));
-	texCoord_interp = tex_rect[0].xw;
+	texCoord_interp = vec2(0.0, 1.0);
 	EmitVertex();
 
 	gl_Position = (ModelViewProjectionMatrix * vec4(pos_rect[0].zw, 0.0, 1.0));
-	texCoord_interp = tex_rect[0].zw;
+	texCoord_interp = vec2(1.0, 1.0);
 	EmitVertex();
 
 	EndPrimitive();
diff --git a/source/blender/gpu/shaders/gpu_shader_text_simple_geom.glsl b/source/blender/gpu/shaders/gpu_shader_text_simple_geom.glsl
index 79dc996997b..8903fd1df57 100644
--- a/source/blender/gpu/shaders/gpu_shader_text_simple_geom.glsl
+++ b/source/blender/gpu/shaders/gpu_shader_text_simple_geom.glsl
@@ -7,27 +7,29 @@ in vec4 tex_rect[];
 in vec4 color[];
 
 flat out vec4 color_flat;
+flat out vec4 texCoord_rect;
 noperspective out vec2 texCoord_interp;
 
 void main()
 {
 	color_flat = color[0];
+	texCoord_rect = tex_rect[0];
 	gl_Position.zw = vec2(0.0, 1.0);
 
 	gl_Position.xy  = pos_rect[0].xy;
-	texCoord_interp = tex_rect[0].xy;
+	texCoord_interp = vec2(0.0, 0.0);
 	EmitVertex();
 
 	gl_Position.xy  = pos_rect[0].zy;
-	texCoord_interp = tex_rect[0].zy;
+	texCoord_interp = vec2(1.0, 0.0);
 	EmitVertex();
 
 	gl_Position.xy  = pos_rect[0].xw;
-	texCoord_interp = tex_rect[0].xw;
+	texCoord_interp = vec2(0.0, 1.0);
 	EmitVertex();
 
 	gl_Position.xy  = pos_rect[0].zw;
-	texCoord_interp = tex_rect[0].zw;
+	texCoord_interp = vec2(1.0, 1.0);
 	EmitVertex();
 
 	EndPrimitive();