Merge pull request #5634 from 06wj/patch_ktx

KhronosTextureContainer: Use DataView to read headers & headers should be Uint32

src/Tools/babylon.khronosTextureContainer.ts

@@ -91,25 +91,24 @@ module BABYLON {
                 return;
             }
 
-            // load the reset of the header in native 32 bit int
-            var header = new Int32Array(this.arrayBuffer, 12, 13);
-
-            // determine of the remaining header values are recorded in the opposite endianness & require conversion
-            var oppositeEndianess = header[0] === 0x01020304;
-
-            // read all the header elements in order they exist in the file, without modification (sans endainness)
-            this.glType = oppositeEndianess ? this.switchEndianness(header[1]) : header[1]; // must be 0 for compressed textures
-            this.glTypeSize = oppositeEndianess ? this.switchEndianness(header[2]) : header[2]; // must be 1 for compressed textures
-            this.glFormat = oppositeEndianess ? this.switchEndianness(header[3]) : header[3]; // must be 0 for compressed textures
-            this.glInternalFormat = oppositeEndianess ? this.switchEndianness(header[4]) : header[4]; // the value of arg passed to gl.compressedTexImage2D(,,x,,,,)
-            this.glBaseInternalFormat = oppositeEndianess ? this.switchEndianness(header[5]) : header[5]; // specify GL_RGB, GL_RGBA, GL_ALPHA, etc (un-compressed only)
-            this.pixelWidth = oppositeEndianess ? this.switchEndianness(header[6]) : header[6]; // level 0 value of arg passed to gl.compressedTexImage2D(,,,x,,,)
-            this.pixelHeight = oppositeEndianess ? this.switchEndianness(header[7]) : header[7]; // level 0 value of arg passed to gl.compressedTexImage2D(,,,,x,,)
-            this.pixelDepth = oppositeEndianess ? this.switchEndianness(header[8]) : header[8]; // level 0 value of arg passed to gl.compressedTexImage3D(,,,,,x,,)
-            this.numberOfArrayElements = oppositeEndianess ? this.switchEndianness(header[9]) : header[9]; // used for texture arrays
-            this.numberOfFaces = oppositeEndianess ? this.switchEndianness(header[10]) : header[10]; // used for cubemap textures, should either be 1 or 6
-            this.numberOfMipmapLevels = oppositeEndianess ? this.switchEndianness(header[11]) : header[11]; // number of levels; disregard possibility of 0 for compressed textures
-            this.bytesOfKeyValueData = oppositeEndianess ? this.switchEndianness(header[12]) : header[12]; // the amount of space after the header for meta-data
+            // load the reset of the header in native 32 bit uint
+            var dataSize = Uint32Array.BYTES_PER_ELEMENT;
+            var headerDataView = new DataView(this.arrayBuffer, 12, 13 * dataSize);
+            var endianness = headerDataView.getUint32(0, true);
+            var littleEndian = endianness === 0x04030201;
+
+            this.glType = headerDataView.getUint32(1 * dataSize, littleEndian); // must be 0 for compressed textures
+            this.glTypeSize = headerDataView.getUint32(2 * dataSize, littleEndian); // must be 1 for compressed textures
+            this.glFormat = headerDataView.getUint32(3 * dataSize, littleEndian); // must be 0 for compressed textures
+            this.glInternalFormat = headerDataView.getUint32(4 * dataSize, littleEndian); // the value of arg passed to gl.compressedTexImage2D(,,x,,,,)
+            this.glBaseInternalFormat = headerDataView.getUint32(5 * dataSize, littleEndian); // specify GL_RGB, GL_RGBA, GL_ALPHA, etc (un-compressed only)
+            this.pixelWidth = headerDataView.getUint32(6 * dataSize, littleEndian); // level 0 value of arg passed to gl.compressedTexImage2D(,,,x,,,)
+            this.pixelHeight = headerDataView.getUint32(7 * dataSize, littleEndian); // level 0 value of arg passed to gl.compressedTexImage2D(,,,,x,,)
+            this.pixelDepth = headerDataView.getUint32(8 * dataSize, littleEndian); // level 0 value of arg passed to gl.compressedTexImage3D(,,,,,x,,)
+            this.numberOfArrayElements = headerDataView.getUint32(9 * dataSize, littleEndian); // used for texture arrays
+            this.numberOfFaces = headerDataView.getUint32(10 * dataSize, littleEndian); // used for cubemap textures, should either be 1 or 6
+            this.numberOfMipmapLevels = headerDataView.getUint32(11 * dataSize, littleEndian); // number of levels; disregard possibility of 0 for compressed textures
+            this.bytesOfKeyValueData = headerDataView.getUint32(12 * dataSize, littleEndian); // the amount of space after the header for meta-data
 
             // Make sure we have a compressed type.  Not only reduces work, but probably better to let dev know they are not compressing.
             if (this.glType !== 0) {
@@ -140,20 +139,6 @@ module BABYLON {
             this.loadType = KhronosTextureContainer.COMPRESSED_2D;
         }
 
-        //
-        /**
-         * Revert the endianness of a value.
-         * Not as fast hardware based, but will probably never need to use
-         * @param val defines the value to convert
-         * @returns the new value
-         */
-        public switchEndianness(val: number): number {
-            return ((val & 0xFF) << 24)
-                | ((val & 0xFF00) << 8)
-                | ((val >> 8) & 0xFF00)
-                | ((val >> 24) & 0xFF);
-        }
-
         /**
          * Uploads KTX content to a Babylon Texture.
          * It is assumed that the texture has already been created & is currently bound