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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>WebGL vertexAttribPointer Conformance Tests</title>
<script src="resources/desktop-gl-constants.js" type="text/javascript"></script>
<script src="../../../resources/js-test.js"></script>
<script src="resources/webgl-test.js"></script>
<script src="resources/webgl-test-utils.js"></script>
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<body>
<div id="description"></div>
<div id="console"></div>
<canvas id="canvas" width="2" height="2"> </canvas>
<script>
description("This test checks vertexAttribPointer behaviors in WebGL.");

debug("");
debug("Canvas.getContext");

if (window.internals)
    window.internals.settings.setWebGLErrorsToConsoleEnabled(false);

var wtu = WebGLTestUtils;
var gl = create3DContext(document.getElementById("canvas"));
if (!gl) {
  testFailed("context does not exist");
} else {
  testPassed("context exists");

  debug("");
  debug("Checking gl.vertexAttribPointer.");

  if (!gl.FIXED) {
    gl.FIXED = 0x140C;
  }

  gl.vertexAttribPointer(0, 3, gl.FLOAT, 0, 0, 12);
  glErrorShouldBe(gl, gl.INVALID_OPERATION,
      "vertexAttribPointer should fail if no buffer is bound");

  var vertexObject = gl.createBuffer();
  gl.bindBuffer(gl.ARRAY_BUFFER, vertexObject);
  gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(0), gl.STATIC_DRAW);

  gl.vertexAttribPointer(0, 1, gl.INT, 0, 0, 0);
  glErrorShouldBe(gl, gl.INVALID_ENUM,
      "vertexAttribPointer should not support INT");
  gl.vertexAttribPointer(0, 1, gl.UNSIGNED_INT, 0, 0, 0);
  glErrorShouldBe(gl, gl.INVALID_ENUM,
      "vertexAttribPointer should not support UNSIGNED_INT");
  gl.vertexAttribPointer(0, 1, gl.FIXED, 0, 0, 0);
  glErrorShouldBe(gl, gl.INVALID_ENUM,
      "vertexAttribPointer should not support FIXED");

  function checkVertexAttribPointer(
      gl, err, reason, size, type, normalize, stride, offset) {
    gl.vertexAttribPointer(0, size, type, normalize, stride, offset);
    glErrorShouldBe(gl, err,
        "gl.vertexAttribPointer(0, " + size +
        ", gl." + wtu.glEnumToString(gl, type) +
        ", " + normalize +
        ", " + stride +
        ", " + offset +
        ") should " + (err == gl.NO_ERROR ? "succeed " : "fail ") + reason);
  }

  var types = [
    { type:gl.BYTE,           bytesPerComponent: 1 },
    { type:gl.UNSIGNED_BYTE,  bytesPerComponent: 1 },
    { type:gl.SHORT,          bytesPerComponent: 2 },
    { type:gl.UNSIGNED_SHORT, bytesPerComponent: 2 },
    { type:gl.FLOAT,          bytesPerComponent: 4 },
  ];

  for (var ii = 0; ii < types.length; ++ii) {
    var info = types[ii];
    debug("");
    for (var size = 1; size <= 4; ++size) {
      debug("");
      debug("checking: " + wtu.glEnumToString(gl, info.type) + " with size " + size);
      var bytesPerElement = size * info.bytesPerComponent;
      var offsetSet;
      if (info.bytesPerComponent > 1)
        offsetSet = [0, info.bytesPerComponent - 1];
      else
        offsetSet = [0];
      for (var jj = 0; jj < offsetSet.length; ++jj) {
        var offset = offsetSet[jj];
        var strideSet;
        if (bytesPerElement > 1)
          strideSet = [0, bytesPerElement - 1, bytesPerElement];
        else
          strideSet = [0, bytesPerElement];
        for (var kk = 0; kk < strideSet.length; ++kk) {
          var stride = strideSet[kk];
          var err = gl.NO_ERROR;
          var reason = ""
          if (offset != 0) {
            reason = "because offset is bad";
            err = gl.INVALID_OPERATION;
          }
          if (stride % info.bytesPerComponent != 0) {
            reason = "because stride is bad";
            err = gl.INVALID_OPERATION;
          }
          checkVertexAttribPointer(
              gl, err, reason, size, info.type, false, stride, offset);
        }
        var stride = Math.floor(255 / info.bytesPerComponent) * info.bytesPerComponent;

        if (offset == 0) {
          checkVertexAttribPointer(
              gl, gl.NO_ERROR, "at stride limit",
              size, info.type, false, stride, offset);
          checkVertexAttribPointer(
              gl, gl.INVALID_VALUE, "over stride limit",
              size, info.type, false,
              stride + info.bytesPerComponent, offset);
        }
      }
    }
  }
}

debug("");

</script>
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