From 09f501939415b70035ae5c1c9fc3a9f3922d4bf3 Mon Sep 17 00:00:00 2001
From: William Wallace <me@wiox.me>
Date: Wed, 12 Jul 2017 10:12:57 +0100
Subject: [PATCH] Improve rendering of masked sprites in OpenGL drawing engine

---
 data/shaders/drawimage.frag | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/data/shaders/drawimage.frag b/data/shaders/drawimage.frag
index 1559de7277..f6f8ed139d 100644
--- a/data/shaders/drawimage.frag
+++ b/data/shaders/drawimage.frag
@@ -59,11 +59,16 @@ void main()
     {
         texel = uPalette[texture(uTexture, vec3(fTexColourCoords, float(fTexColourAtlas))).r];
     }
-    vec4 mask = uPalette[texture(uTexture, vec3(fTexMaskCoords, float(fTexMaskAtlas))).r];
 
     if (fMask != 0)
     {
-        oColour = texel * mask;
+        float mask = texture(uTexture, vec3(fTexMaskCoords, float(fTexMaskAtlas))).r;
+        if ( mask == 0.0 )
+        {
+            discard;
+        }
+
+        oColour = texel;
     }
     else
     {