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** Permission is hereby granted, free of charge, to any person obtaining a
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<!DOCTYPE html>
<html>
  <head>
<meta charset="utf-8">
    <title>vertexattribpointer offsets test</title>
    <link rel="stylesheet" href="../../resources/js-test-style.css"/>
    <script src="../../resources/js-test-pre.js"></script>
    <script src="../resources/webgl-test-utils.js"> </script>
</head>
<body>
<canvas id="example" width="50" height="50">
There is supposed to be an example drawing here, but it's not important.
</canvas>
<div id="description"></div>
<div id="console"></div>
    <script id="vshader" type="x-shader/x-vertex">
        attribute vec4 vPosition;
        void main()
        {
            gl_Position = vPosition;
        }
    </script>

    <script id="fshader" type="x-shader/x-fragment">
        precision mediump float;
        uniform vec4 color;
        void main()
        {
            gl_FragColor = color;
        }
    </script>

    <script>
        "use strict";
        function init()
        {
            description("test vertexattribpointer offsets work");

            var wtu = WebGLTestUtils;
            var gl = wtu.create3DContext("example");
            var program = wtu.setupProgram(gl, ["vshader", "fshader"], ["vPosition"]);

            var tests = [
              { data: new Float32Array([ 0, 1, 0, 1, 0, 0, 0, 0, 0 ]),
                type: gl.FLOAT,
                componentSize: 4,
                normalize: false,
              },
              { data: new Float32Array([ 0, 1, 0, 1, 0, 0, 0, 0, 0 ]),
                type: gl.FLOAT,
                componentSize: 4,
                normalize: false,
              },
              { data: new Uint16Array([ 0, 32767, 0, 32767, 0, 0, 0, 0, 0 ]),
                type: gl.SHORT,
                componentSize: 2,
                normalize: true,
              },
              { data: new Uint16Array([ 0, 65535, 0, 65535, 0, 0, 0, 0, 0 ]),
                type: gl.UNSIGNED_SHORT,
                componentSize: 2,
                normalize: true,
              },
              { data: new Uint16Array([ 0, 1, 0, 1, 0, 0, 0, 0, 0 ]),
                type: gl.UNSIGNED_SHORT,
                componentSize: 2,
                normalize: false,
              },
              { data: new Uint16Array([ 0, 1, 0, 1, 0, 0, 0, 0, 0 ]),
                type: gl.SHORT,
                componentSize: 2,
                normalize: false,
              },
              { data: new Uint8Array([ 0, 127, 0, 127, 0, 0, 0, 0, 0 ]),
                type: gl.BYTE,
                componentSize: 1,
                normalize: true,
              },
              { data: new Uint8Array([ 0, 255, 0, 255, 0, 0, 0, 0, 0 ]),
                type: gl.UNSIGNED_BYTE,
                componentSize: 1,
                normalize: true,
              },
              { data: new Uint8Array([ 0, 1, 0, 1, 0, 0, 0, 0, 0 ]),
                type: gl.BYTE,
                componentSize: 1,
                normalize: false,
              },
              { data: new Uint8Array([ 0, 1, 0, 1, 0, 0, 0, 0, 0 ]),
                type: gl.UNSIGNED_BYTE,
                componentSize: 1,
                normalize: false,
              }
            ];

            var vertexObject = gl.createBuffer();
            gl.bindBuffer(gl.ARRAY_BUFFER, vertexObject);
            gl.bufferData(gl.ARRAY_BUFFER, 1024, gl.STATIC_DRAW);
            gl.enableVertexAttribArray(0);

            var colorLoc = gl.getUniformLocation(program, "color");
            var kNumVerts = 3;
            var kNumComponents = 3;

            var count = 0;
            for (var tt = 0; tt < tests.length; ++tt) {
              var test = tests[tt];
              for (var oo = 0; oo < 3; ++oo) {
                for (var ss = 0; ss < 3; ++ss) {
                  var offset = (oo + 1) * test.componentSize;
                  var color = (count % 2) ? [1, 0, 0, 1] : [0, 1, 0, 1];
                  var stride = test.componentSize * kNumComponents + test.componentSize * ss;
                  debug("");
                  debug("check with " + wtu.glEnumToString(gl, test.type) + " at offset: " + offset + " with stride:" + stride + " normalize: " + test.normalize);
                  gl.uniform4fv(colorLoc, color);
                  var data = new Uint8Array(test.componentSize * kNumVerts * kNumComponents + stride * (kNumVerts - 1));
                  var view = new Uint8Array(test.data.buffer);
                  var size = test.componentSize * kNumComponents;
                  for (var jj = 0; jj < kNumVerts; ++jj) {
                    var off1 = jj * size;
                    var off2 = jj * stride;
                    for (var zz = 0; zz < size; ++zz) {
                      data[off2 + zz] = view[off1 + zz];
                    }
                  }
                  gl.bufferSubData(gl.ARRAY_BUFFER, offset, data);
                  gl.vertexAttribPointer(0, 3, test.type, test.normalize, stride, offset);
                  gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
                  gl.drawArrays(gl.TRIANGLES, 0, 3);

                  var buf = new Uint8Array(50 * 50 * 4);
                  gl.readPixels(0, 0, 50, 50, gl.RGBA, gl.UNSIGNED_BYTE, buf);

                  var black = [0, 0, 0, 0];
                  var other = [color[0] * 255, color[1] * 255, color[2] * 255, color[3] * 255];
                  var otherMsg = "should be " + ((count % 2) ? "red" : "green")
                  wtu.checkCanvasRect(gl, 0, 0, 1, 1, black, "should be black", 0);
                  wtu.checkCanvasRect(gl, 0, 49, 1, 1, black, "should be black", 0);
                  wtu.checkCanvasRect(gl, 26, 40, 1, 1, other, otherMsg, 0);
                  wtu.checkCanvasRect(gl, 26, 27, 1, 1, other, otherMsg, 0);
                  wtu.checkCanvasRect(gl, 40, 27, 1, 1, other, otherMsg, 0);
                  ++count;
                }
              }
            }
       }

       init();
       var successfullyParsed = true;
    </script>
<script src="../../resources/js-test-post.js"></script>

</body>
</html>
