nidza/src/lib/base-shader-component.js

Nidza.js is ultimate canvas2d+3d solution. In context of 3d graphics it is used for GLSL manipulation. Objective is low CPU usage price.

export class BaseShader {
  constructor() {
    console.log("SHADER BASE CLASS");
  }

  /**
   * Creates and compiles a shader.
   *
   * @param {!WebGLRenderingContext} gl The WebGL Context.
   * @param {string} shaderSource The GLSL source code for the shader.
   * @param {number} shaderType The type of shader, VERTEX_SHADER or
   *     FRAGMENT_SHADER.
   * @return {!WebGLShader} The shader.
   */
  compileShader(gl, shaderType, shaderSource) {
    // Create the shader object
    var shader = gl.createShader(shaderType);
    // Set the shader source code.
    gl.shaderSource(shader, shaderSource);
    // Compile the shader
    gl.compileShader(shader);
    // Check if it compiled
    var success = gl.getShaderParameter(shader, gl.COMPILE_STATUS);
    if (!success) {
      // Something went wrong during compilation; get the error
      throw "could not compile shader:" + gl.getShaderInfoLog(shader);
    }

    return shader;
  }

  /**
   * Creates a program from 2 shaders.
   *
   * @param {!WebGLRenderingContext) gl The WebGL context.
   * @param {!WebGLShader} vertexShader A vertex shader.
   * @param {!WebGLShader} fragmentShader A fragment shader.
   * @return {!WebGLProgram} A program.
   */
  createProgram(gl, vertexShader, fragmentShader) {
    // create a program.
    var program = gl.createProgram();
    // attach the shaders.
    gl.attachShader(program, vertexShader);
    gl.attachShader(program, fragmentShader);
    // link the program.
    gl.linkProgram(program);
    // Check if it linked.
    var success = gl.getProgramParameter(program, gl.LINK_STATUS);
    if (!success) {
      // something went wrong with the link
      throw "program failed to link:" + gl.getProgramInfoLog(program);
    }
    return program;
  }

  /**
   * Creates a shader from the content of a script tag.
   *
   * @param {!WebGLRenderingContext} gl The WebGL Context.
   * @param {string} scriptId The id of the script tag.
   * @param {string} opt_shaderType. The type of shader to create.
   *     If not passed in will use the type attribute from the
   *     script tag.
   * @return {!WebGLShader} A shader.
   */
  createShaderFromScript(gl, scriptId, opt_shaderType) {
    // look up the script tag by id.
    var shaderScript = document.getElementById(scriptId);
    if (!shaderScript) {
      throw "*** Error: unknown script element" + scriptId;
    }

    // extract the contents of the script tag.
    var shaderSource = shaderScript.text;
    // If we didn't pass in a type, use the 'type' from
    // the script tag.
    if (!opt_shaderType) {
      if (shaderScript.type == "x-shader/x-vertex") {
        opt_shaderType = gl.VERTEX_SHADER;
      } else if (shaderScript.type == "x-shader/x-fragment") {
        opt_shaderType = gl.FRAGMENT_SHADER;
      } else if (!opt_shaderType) {
        throw "*** Error: shader type not set";
      }
    }

    return compileShader(gl, shaderSource, opt_shaderType);
  }

  // init Shader PRogram from inline 
  initShaderProgram(gl, vsSource, fsSource) {
    const vertexShader = this.compileShader(gl, gl.VERTEX_SHADER, vsSource);
    const fragmentShader = this.compileShader(gl, gl.FRAGMENT_SHADER, fsSource);

    // Create the shader program
    const shaderProgram = gl.createProgram();
    gl.attachShader(shaderProgram, vertexShader);
    gl.attachShader(shaderProgram, fragmentShader);
    gl.linkProgram(shaderProgram);

    // If creating the shader program failed, alert
    if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
      alert(
        "Unable to initialize the shader program: " +
          gl.getProgramInfoLog(shaderProgram)
      );
      return null;
    }

    return shaderProgram;
  }

  /**
   * Creates a program from 2 script tags.
   * @param {!WebGLRenderingContext} gl The WebGL Context.
   * @param {string[]} shaderScriptIds Array of ids of the script
   *        tags for the shaders. The first is assumed to be the
   *        vertex shader, the second the fragment shader.
   * @return {!WebGLProgram} A program
   */
  createProgramFromScripts(gl, shaderScriptIds) {
    var vertexShader = createShaderFromScript(
      gl,
      shaderScriptIds[0],
      gl.VERTEX_SHADER
    );
    var fragmentShader = createShaderFromScript(
      gl,
      shaderScriptIds[1],
      gl.FRAGMENT_SHADER
    );
    return createProgram(gl, vertexShader, fragmentShader);
  }
}