M CHANGES → CHANGES

@@ -12,6 +12,7 @@ - GBA Video: Don't draw sprites using unmapped VRAM in GL renderer (fixes mgba.io/i/1865)
  - GBA Video: Fix rare regression blending semitransparent sprites (fixes mgba.io/i/1876)
  - GBA Video: Do not affect OBJ pixel priority when writing OBJWIN (fixes mgba.io/i/1890)
  - GBA Video: Fix deferred blending when OBJWIN matches window (fixes mgba.io/i/1905)
+ - GBA Video: Fix mode 4 transparency in OpenGL (fixes mgba.io/i/1907)
 Other fixes:
  - 3DS: Redo video sync to be more precise
  - 3DS: Fix crash with libctru 2.0 when exiting

M src/gba/renderers/gl.c → src/gba/renderers/gl.c

@@ -410,8 +410,11 @@ "		discard;\n"
 	"	}\n"
 	"	int address = charBase + (coord.x >> 8) + (coord.y >> 8) * size.x;\n"
 	"	vec4 twoEntries = texelFetch(vram, ivec2((address >> 1) & 255, address >> 9), 0);\n"
-	"	ivec2 entry = ivec2(twoEntries[3 - 2 * (address & 1)] * 15.9, twoEntries[2 - 2 * (address & 1)] * 15.9);\n"
-	"	int paletteEntry = palette[entry.y * 16 + entry.x];\n"
+	"	int entry = int(twoEntries[2 - 2 * (address & 1)] * 15.9) * 16 + int(twoEntries[3 - 2 * (address & 1)] * 15.9);\n"
+	"	if (entry == 0) {\n"
+	"		discard;\n"
+	"	}\n"
+	"	int paletteEntry = palette[entry];\n"
 	"	color = vec4(PALETTE_ENTRY(paletteEntry), 1.);\n"
 	"	flags = inflags;\n"
 	"}";