/*******************************************************************************
* Copyright 2011 See AUTHORS file.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
******************************************************************************/
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;
}
}