Implement glBufferSubData

2 files changed, 12 insertions, 4 deletions

diff --git a/src/library_gl.js b/src/library_gl.js
index 73ab72da..3583f366 100644
--- a/src/library_gl.js
+++ b/src/library_gl.js
@@ -235,6 +235,11 @@ var LibraryGL = {
     Module.ctx.bufferData(target, floatArray, usage);
   },
 
+  glBufferSubData: function(target, offset, size, data) {
+    var floatArray = new Float32Array(TypedArray_copy(data, size, offset));
+    Module.ctx.bufferSubData(target, offset, floatArray);
+  },
+
   glGenRenderbuffers__deps: ['$GL'],
   glGenRenderbuffers: function(n, renderbuffers) {
     for (var i = 0; i < n; i++) {
diff --git a/src/preamble.js b/src/preamble.js
index 0e43af12..d56891d0 100644
--- a/src/preamble.js
+++ b/src/preamble.js
@@ -729,11 +729,14 @@ Module['Array_copy'] = Array_copy;
 #if USE_TYPED_ARRAYS
 // Copies a list of num items on the HEAP into a
 // JavaScript typed array.
-function TypedArray_copy(ptr, num) {
+function TypedArray_copy(ptr, num, offset /*optional*/) {
   // TODO: optimize this!
-  var arr = new Uint8Array(num);
-  for (var i = 0; i < num; ++i) {
-    arr[i] = {{{ makeGetValue('ptr', 'i', 'i8') }}};
+  if (offset === undefined) {
+    offset = 0;
+  }
+  var arr = new Uint8Array(num - offset);
+  for (var i = offset; i < num; ++i) {
+    arr[i - offset] = {{{ makeGetValue('ptr', 'i', 'i8') }}};
   }
   return arr.buffer;
 }