1 files changed, 21 insertions, 2 deletions
diff --git a/res/text.f.glsl b/res/text.f.glsl
index ce9dd41e..7e80a11c 100644
--- a/res/text.f.glsl
+++ b/res/text.f.glsl
@@ -3,9 +3,28 @@ in vec2 TexCoords;
 
 uniform sampler2D mask;
 uniform vec3 textColor;
+uniform vec3 bgColor;
+
+// SRC = SRC_ALPHA; DST = 1 - SRC_ALPHA
+void MyBlend(in vec3 srcValue,
+             in vec3 dstValue,
+             in vec3 srcAlpha,
+             out vec3 blended)
+{
+    vec3 dstAlpha = vec3(1.0, 1.0, 1.0) - srcAlpha;
+    vec3 preBlended = (srcValue * srcAlpha + dstValue * dstAlpha);
+
+    blended = vec3(min(1.0, preBlended.x),
+                   min(1.0, preBlended.y),
+                   min(1.0, preBlended.z));
+}
 
 void main()
 {
-    vec4 sampled = vec4(1.0, 1.0, 1.0, texture(mask, TexCoords).r);
-    gl_FragColor = vec4(textColor, 1.0) * sampled;
+    // vec4 red = vec4(sampled.rgb, sampled.r * sampled.g * sampled.b);
+    // vec4 sampled = vec4(1.0, 1.0, 1.0, texture(mask, TexCoords));
+    vec3 blended = vec3(1.0, 1.0, 1.0);
+    MyBlend(textColor, bgColor, texture(mask, TexCoords).rgb, blended);
+
+    gl_FragColor = vec4(blended, 1.0);
 }