WebGL: enablevertexattribarray index out of range

Question

Here are my vertex and fragment shaders:

<script id="shader-fs" type="x-shader/x-fragment"> precision mediump float; uniform sampler2D uSampler; varying vec4 vColor; varying vec2 vTextureCoord; void main(void) { gl_FragColor = vColor; // gl_FragColor = texture2D(uSampler, vec2(vTextureCoord.s, vTextureCoord.t)); } </script> <script id="shader-vs" type="x-shader/x-vertex"> attribute vec3 aVertexPosition; attribute vec4 aVertexColor; attribute vec2 aTextureCoord; uniform mat4 uMVMatrix; uniform mat4 uPMatrix; varying vec4 vColor; varying vec2 vTextureCoord; void main(void) { gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0); vColor = aVertexColor; // vTextureCoord = aTextureCoord; } </script> 

And here is my shader initializer:

 function initShaders() { var fragmentShader = getShader(gl, "shader-fs"); var vertexShader = getShader(gl, "shader-vs"); shaderProgram = gl.createProgram(); gl.attachShader(shaderProgram, vertexShader); gl.attachShader(shaderProgram, fragmentShader); gl.linkProgram(shaderProgram); if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) { alert("Could not initialise shaders"); } gl.useProgram(shaderProgram); shaderProgram.vertexPositionAttribute = gl.getAttribLocation(shaderProgram, "aVertexPosition"); gl.enableVertexAttribArray(shaderProgram.vertexPositionAttribute); shaderProgram.vertexColorAttribute = gl.getAttribLocation(shaderProgram, "aVertexColor"); gl.enableVertexAttribArray(shaderProgram.vertexColorAttribute); shaderProgram.textureCoordAttribute = gl.getAttribLocation(shaderProgram, "aTextureCoord"); gl.enableVertexAttribArray(shaderProgram.textureCoordAttribute); shaderProgram.pMatrixUniform = gl.getUniformLocation(shaderProgram, "uPMatrix"); shaderProgram.mvMatrixUniform = gl.getUniformLocation(shaderProgram, "uMVMatrix"); shaderProgram.samplerUniform = gl.getUniformLocation(shaderProgram, "uSampler"); } 

The error occurs from this line:

  gl.enableVertexAttribArray(shaderProgram.textureCoordAttribute); >> enablevertexattribarray index out of range 

How can I handle this?

Answer 1

This is simply because you are not using aTextureCoord in your vertex program, so the GLSL-Compiler optimizes it by deleting it. You really have to check the result of gl.GetAttribLocation () for errors and include only those attributes that are present in your program. Issuing a warning in the absence of an attribute will be sufficient; I don’t know how to distinguish errors in creating shaders from optimizations by the compiler.