Function Shader

src/ui/viewer/lightgl.js:833–931

(vertexSource, fragmentSource)

	function Shader(vertexSource, fragmentSource) {
		// Allow passing in the id of an HTML script tag with the source


		function followScriptTagById(id) {
			var element = document.getElementById(id);
			return element ? element.text : id;
		}
		vertexSource = followScriptTagById(vertexSource);
		fragmentSource = followScriptTagById(fragmentSource);

		// Headers are prepended to the sources to provide some automatic functionality.
		var header = '\
    uniform mat3 gl_NormalMatrix;\
    uniform mat4 gl_ModelViewMatrix;\
    uniform mat4 gl_ProjectionMatrix;\
    uniform mat4 gl_ModelViewProjectionMatrix;\
    uniform mat4 gl_ModelViewMatrixInverse;\
    uniform mat4 gl_ProjectionMatrixInverse;\
    uniform mat4 gl_ModelViewProjectionMatrixInverse;\
  ';
		var vertexHeader = header + '\
    attribute vec4 gl_Vertex;\
    attribute vec4 gl_TexCoord;\
    attribute vec3 gl_Normal;\
    attribute vec4 gl_Color;\
    vec4 ftransform() {\
      return gl_ModelViewProjectionMatrix * gl_Vertex;\
    }\
  ';
		var fragmentHeader = '\
    precision highp float;\
  ' + header;

		// Check for the use of built-in matrices that require expensive matrix
		// multiplications to compute, and record these in `usedMatrices`.
		var source = vertexSource + fragmentSource;
		var usedMatrices = {};
		regexMap(/\b(gl_[^;]*)\b;/g, header, function(groups) {
			var name = groups[1];
			if(source.indexOf(name) != -1) {
				var capitalLetters = name.replace(/[a-z_]/g, '');
				usedMatrices[capitalLetters] = LIGHTGL_PREFIX + name;
			}
		});
		if(source.indexOf('ftransform') != -1) usedMatrices.MVPM = LIGHTGL_PREFIX + 'gl_ModelViewProjectionMatrix';
		this.usedMatrices = usedMatrices;

		// The `gl_` prefix must be substituted for something else to avoid compile
		// errors, since it's a reserved prefix. This prefixes all reserved names with
		// `_`. The header is inserted after any extensions, since those must come
		// first.


		function fix(header, source) {
			var replaced = {};
			var match = /^((\s*\/\/.*\n|\s*#extension.*\n)+)\^*$/.exec(source);
			source = match ? match[1] + header + source.substr(match[1].length) : header + source;