WebGLUtil.java

package com.google.gwt.webgl.client;

import static com.google.gwt.webgl.client.WebGLRenderingContext.*;

public class WebGLUtil {

  public static float[] createPerspectiveMatrix(int fieldOfViewVertical,
      float aspectRatio, float minimumClearance, float maximumClearance) {
    double fieldOfViewInRad = fieldOfViewVertical * Math.PI / 180.0;
    return new float[]{
        (float) (Math.tan(fieldOfViewInRad) / aspectRatio),
        0,
        0,
        0,
        0,
        (float) (1 / Math.tan(fieldOfViewVertical * Math.PI / 180.0)),
        0,
        0,
        0,
        0,
        (minimumClearance + maximumClearance)
            / (minimumClearance - maximumClearance),
        -1,
        0,
        0,
        2 * minimumClearance * maximumClearance
            / (minimumClearance - maximumClearance), 0};
  }

  public static WebGLProgram createShaderProgram(WebGLRenderingContext gl,
      String vertexSource, String fragmentSource) {
    WebGLShader vertexShader = getShader(gl, VERTEX_SHADER, vertexSource);
    WebGLShader fragmentShader = getShader(gl, FRAGMENT_SHADER, fragmentSource);

    WebGLProgram shaderProgram = gl.createProgram();
    gl.attachShader(shaderProgram, fragmentShader);
    gl.attachShader(shaderProgram, vertexShader);
    gl.linkProgram(shaderProgram);

    if (!gl.getProgramParameterb(shaderProgram, LINK_STATUS)) {
      throw new RuntimeException("Could not initialize shaders");
    }

    return shaderProgram;
  }

  private static WebGLShader getShader(WebGLRenderingContext gl,
      int shaderType, String source) {
    WebGLShader shader = gl.createShader(shaderType);
    gl.shaderSource(shader, source);
    gl.compileShader(shader);
    if (!gl.getShaderParameterb(shader, COMPILE_STATUS)) {
      throw new RuntimeException(gl.getShaderInfoLog(shader));
    }
    return shader;
  }
}