Source: shaders/point_shader.js

  1. /* 
  2.  * File: point_shader.js
  3.  *          for particle engine
  4.  */
  5. "use strict";
  7. import * as glSys from "../core/gl.js";
  8. import * as vertexBuffer from "../core/vertex_buffer.js";
  9. import SimpleShader from "./simple_shader.js";
  11. class PointShader extends SimpleShader {
  12.     /**
  13.      * @constructor PointShader
  14.      * @param {string} vertexShaderPath - Path to the vertex shader
  15.      * @param {string} fragmentShaderPath - Path to the fragment shader
  16.      */
  17.     constructor(vertexShaderPath, fragmentShaderPath) {
  18.         super(vertexShaderPath, fragmentShaderPath);
  19.         let gl = glSys.get();
  21.         this.mPointSizeRef = null;            // reference to the PointSize uniform
  23.         // point size uniform
  24.         this.mPointSizeRef = gl.getUniformLocation(this.mCompiledShader, "uPointSize");
  26.         this.mPointSize = 1;
  27.     }
  29.     /**
  30.      * @function activate() - Activates the shader for rendering
  31.      * @param {vec4} pixelColor - The color that is referenced in the fragment shader
  32.      * @param {mat4} trsMatrix - The transform matrix
  33.      * @param {mat4} cameraMatrix - The camera matrix
  34.      */
  35.     // Activate the shader for rendering
  36.     activate(pixelColor, trsMatrix, cameraMatrix) {
  37.         // first call the super class' activate
  38.         super.activate(pixelColor, trsMatrix, cameraMatrix);
  40.         // now our own functionality: load the pixel size
  41.         let gl = glSys.get();
  42.         gl.uniform1f(this.mPointSizeRef, this.mPointSize);
  44.         // re-bind the vertex position attribute to the pixel's buffer
  45.         gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer.getPointVertexBuffer());
  46.         gl.vertexAttribPointer(this.mVertexPositionRef,  // this is defined in SimpleShader
  47.             3,              // each element is a 3-float (x,y.z)
  48.             gl.FLOAT,       // data type is FLOAT
  49.             false,          // if the content is normalized vectors
  50.             0,              // number of bytes to skip in between elements
  51.             0);
  52.         gl.enableVertexAttribArray(this.mVertexPositionRef);
  53.     }
  54.     /**
  55.      * @function setPointSize() - sets the pixel size to allow resizing
  56.      * @param {float} w - the new pixel size
  57.      */
  58.     setPointSize(w) { 
  59.         this.mPointSize = w;
  60.     }
  61. }
  63. export default PointShader;