From 29df3df4f2b5eeb5050653678a287cbc7e143886 Mon Sep 17 00:00:00 2001
From: Alon Zakai <alonzakai@gmail.com>
Date: Fri, 15 Feb 2013 13:44:53 +0100
Subject: ensure no writes out of the buffer area in glReadPixels

---
 src/library_gl.js | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

(limited to 'src')

diff --git a/src/library_gl.js b/src/library_gl.js
index 8f692dbf..1f664717 100644
--- a/src/library_gl.js
+++ b/src/library_gl.js
@@ -408,7 +408,19 @@ var LibraryGL = {
   },
 
   glReadPixels: function(x, y, width, height, format, type, pixels) {
-    Module.ctx.readPixels(x, y, width, height, format, type, HEAPU8.subarray(pixels));
+    assert(type == 0x1401 /* GL_UNSIGNED_BYTE */);
+    var sizePerPixel;
+    switch (format) {
+      case 0x1907 /* GL_RGB */:
+        sizePerPixel = 3;
+        break;
+      case 0x1908 /* GL_RGBA */:
+        sizePerPixel = 4;
+        break;
+      default: throw 'unsupported glReadPixels format';
+    }
+    var totalSize = width*height*sizePerPixel;
+    Module.ctx.readPixels(x, y, width, height, format, type, HEAPU8.subarray(pixels, pixels + totalSize));
   },
 
   glBindTexture: function(target, texture) {
-- 
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