2 files changed, 67 insertions, 26 deletions

diff --git a/alacritty/res/glsl3/text.f.glsl b/alacritty/res/glsl3/text.f.glsl
index eddc1734..1930e354 100644
--- a/alacritty/res/glsl3/text.f.glsl
+++ b/alacritty/res/glsl3/text.f.glsl
@@ -1,40 +1,73 @@
+#if defined(GLES2_RENDERER)
+// Require extension for dual source blending to work on GLES2.
+#extension GL_EXT_blend_func_extended: require
+
+#define int_t highp int
+#define float_t highp float
+#define vec3_t mediump vec3
+#define texture texture2D
+
+varying mediump vec2 TexCoords;
+varying mediump vec3 fg;
+varying highp float colored;
+varying mediump vec4 bg;
+
+#define FRAG_COLOR gl_FragColor
+#define ALPHA_MASK gl_SecondaryFragColorEXT
+#else
+
+#define int_t int
+#define float_t float
+#define vec3_t vec3
+
 in vec2 TexCoords;
 flat in vec4 fg;
 flat in vec4 bg;
-uniform int backgroundPass;
 
 layout(location = 0, index = 0) out vec4 color;
 layout(location = 0, index = 1) out vec4 alphaMask;
 
-uniform sampler2D mask;
+#define FRAG_COLOR color
+#define ALPHA_MASK alphaMask
+#endif
 
-#define COLORED 2
+#define COLORED 1
+
+uniform int_t renderingPass;
+uniform sampler2D mask;
 
 void main() {
-    if (backgroundPass != 0) {
+    if (renderingPass == 0) {
         if (bg.a == 0.0) {
             discard;
         }
 
-        alphaMask = vec4(1.0);
-
+        ALPHA_MASK = vec4(1.0);
         // Premultiply background color by alpha.
-        color = vec4(bg.rgb * bg.a, bg.a);
-    } else if ((int(fg.a) & COLORED) != 0) {
+        FRAG_COLOR = vec4(bg.rgb * bg.a, bg.a);
+        return;
+    }
+
+#if !defined(GLES2_RENDERER)
+    float_t colored = fg.a;
+#endif
+
+    // The wide char information is already stripped, so it's safe to check for equality here.
+    if (int(colored) == COLORED) {
         // Color glyphs, like emojis.
-        vec4 glyphColor = texture(mask, TexCoords);
-        alphaMask = vec4(glyphColor.a);
+        FRAG_COLOR = texture(mask, TexCoords);
+        ALPHA_MASK = vec4(FRAG_COLOR.a);
 
         // Revert alpha premultiplication.
-        if (glyphColor.a != 0) {
-            glyphColor.rgb = vec3(glyphColor.rgb / glyphColor.a);
+        if (FRAG_COLOR.a != 0.0) {
+            FRAG_COLOR.rgb = vec3(FRAG_COLOR.rgb / FRAG_COLOR.a);
         }
 
-        color = vec4(glyphColor.rgb, 1.0);
+        FRAG_COLOR = vec4(FRAG_COLOR.rgb, 1.0);
     } else {
         // Regular text glyphs.
-        vec3 textColor = texture(mask, TexCoords).rgb;
-        alphaMask = vec4(textColor, textColor.r);
-        color = vec4(fg.rgb, 1.0);
+        vec3_t textColor = texture(mask, TexCoords).rgb;
+        ALPHA_MASK = vec4(textColor, textColor.r);
+        FRAG_COLOR = vec4(fg.rgb, 1.0);
     }
 }
diff --git a/alacritty/res/glsl3/text.v.glsl b/alacritty/res/glsl3/text.v.glsl
index 5c22e0e6..7e0cd881 100644
--- a/alacritty/res/glsl3/text.v.glsl
+++ b/alacritty/res/glsl3/text.v.glsl
@@ -23,9 +23,9 @@ flat out vec4 bg;
 uniform vec2 cellDim;
 uniform vec4 projection;
 
-uniform int backgroundPass;
+uniform int renderingPass;
 
-#define WIDE_CHAR 1
+#define WIDE_CHAR 2
 
 void main() {
     vec2 projectionOffset = projection.xy;
@@ -39,12 +39,23 @@ void main() {
     // Position of cell from top-left
     vec2 cellPosition = cellDim * gridCoords;
 
-    if (backgroundPass != 0) {
+    fg = vec4(textColor.rgb / 255.0, textColor.a);
+    bg = backgroundColor / 255.0;
+
+    float occupiedCells = 1;
+    if ((int(fg.a) >= WIDE_CHAR)) {
+        // Update wide char x dimension so it'll cover the following spacer.
+        occupiedCells = 2;
+
+        // Since we don't perform bitwise operations due to limitations of
+        // the GLES2 renderer,we subtract wide char bits keeping only colored.
+        fg.a = round(fg.a - WIDE_CHAR);
+    }
+
+    if (renderingPass == 0) {
         vec2 backgroundDim = cellDim;
-        if ((int(textColor.a) & WIDE_CHAR) != 0) {
-            // Update wide char x dimension so it'll cover the following spacer.
-            backgroundDim.x *= 2;
-        }
+        backgroundDim.x *= occupiedCells;
+
         vec2 finalPosition = cellPosition + backgroundDim * position;
         gl_Position =
             vec4(projectionOffset + projectionScale * finalPosition, 0.0, 1.0);
@@ -63,7 +74,4 @@ void main() {
         vec2 uvSize = uv.zw;
         TexCoords = uvOffset + position * uvSize;
     }
-
-    bg = backgroundColor / 255.0;
-    fg = vec4(textColor.rgb / 255.0, textColor.a);
 }