ShaderProgram.java

/**
 * Copyright (c) 2012, Matt DesLauriers All rights reserved.
 *
 *	Redistribution and use in source and binary forms, with or without
 *	modification, are permitted provided that the following conditions are met: 
 *
 *	* Redistributions of source code must retain the above copyright notice, this
 *	  list of conditions and the following disclaimer. 
 *
 *	* Redistributions in binary
 *	  form must reproduce the above copyright notice, this list of conditions and
 *	  the following disclaimer in the documentation and/or other materials provided
 *	  with the distribution. 
 *
 *	* Neither the name of the Matt DesLauriers nor the names
 *	  of his contributors may be used to endorse or promote products derived from
 *	  this software without specific prior written permission.
 *
 *	THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 *	AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 *	IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 *	ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 *	LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 *	CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 *	SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 *	INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 *	CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 *	ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 *	POSSIBILITY OF SUCH DAMAGE.
 */
package mdesl.graphics.glutils;

import static org.lwjgl.opengl.GL11.GL_FALSE;
import static org.lwjgl.opengl.GL20.GL_COMPILE_STATUS;
import static org.lwjgl.opengl.GL20.GL_FRAGMENT_SHADER;
import static org.lwjgl.opengl.GL20.GL_INFO_LOG_LENGTH;
import static org.lwjgl.opengl.GL20.GL_LINK_STATUS;
import static org.lwjgl.opengl.GL20.GL_VERTEX_SHADER;
import static org.lwjgl.opengl.GL20.glAttachShader;
import static org.lwjgl.opengl.GL20.glBindAttribLocation;
import static org.lwjgl.opengl.GL20.glCompileShader;
import static org.lwjgl.opengl.GL20.glCreateProgram;
import static org.lwjgl.opengl.GL20.glCreateShader;
import static org.lwjgl.opengl.GL20.glDeleteProgram;
import static org.lwjgl.opengl.GL20.glDeleteShader;
import static org.lwjgl.opengl.GL20.glDetachShader;
import static org.lwjgl.opengl.GL20.glGetProgram;
import static org.lwjgl.opengl.GL20.glGetProgramInfoLog;
import static org.lwjgl.opengl.GL20.glGetShader;
import static org.lwjgl.opengl.GL20.glGetShaderInfoLog;
import static org.lwjgl.opengl.GL20.glGetUniformLocation;
import static org.lwjgl.opengl.GL20.glLinkProgram;
import static org.lwjgl.opengl.GL20.glShaderSource;
import static org.lwjgl.opengl.GL20.glUseProgram;

import java.util.List;

/**
 * A bare-bones ShaderProgram utility based on ra4king's ArcSynthesis Java ports. 
 * 
 * @author ra4king, modifications by davedes
 */
public class ShaderProgram {

	public final int program;
	public final int vertex;
	public final int fragment;
	protected String log;
	
	public ShaderProgram(String vertexSource, String fragmentSource) {
		this(vertexSource, fragmentSource, null);
	}

	public ShaderProgram(String vertexShader, String fragmentShader, List<VertexAttrib> attributes) {
		vertex = compileShader(vertexShader, GL_VERTEX_SHADER);
		fragment = compileShader(fragmentShader, GL_FRAGMENT_SHADER);
		program = glCreateProgram();
		glAttachShader(program, vertex);
		glAttachShader(program, fragment);
		
		if (attributes != null)
			for (VertexAttrib a : attributes)
				glBindAttribLocation(program, a.location, a.name);
		
		glLinkProgram(program);
		
		String infoLog = glGetProgramInfoLog(program, glGetProgram(program, GL_INFO_LOG_LENGTH));
		
		if (glGetProgram(program, GL_LINK_STATUS) == GL_FALSE)
			throw new RuntimeException(
					"Failure in linking program. Error log:\n" + infoLog);
		
		if (infoLog!=null && infoLog.trim().length()!=0)
			log += infoLog;
				
		glDetachShader(program, vertex);
		glDetachShader(program, fragment);
		glDeleteShader(vertex);
		glDeleteShader(fragment);
	}
		
	private int compileShader(String source, int type) {
		int shader = glCreateShader(type);
		glShaderSource(shader, source);
		glCompileShader(shader);
		
		String infoLog = glGetShaderInfoLog(shader,
				glGetShader(shader, GL_INFO_LOG_LENGTH));

		if (glGetShader(shader, GL_COMPILE_STATUS) == GL_FALSE)
			throw new RuntimeException("Failure in compiling " + getName(type)
					+ ". Error log:\n" + infoLog);
		
		if (infoLog!=null && infoLog.trim().length()!=0)
			log += getName(type) +": "+infoLog + "\n";
		
		return shader;
	}

	private String getName(int shaderType) {
		if (shaderType == GL_VERTEX_SHADER)
			return "GL_VERTEX_SHADER";
		if (shaderType == GL_FRAGMENT_SHADER)
			return "GL_FRAGMENT_SHADER";
		else 
			return "shader";
	}

	public void begin() {
		glUseProgram(program);
	}

	public void end() {
		glUseProgram(0);
	}
	
	public void destroy() {		
		glDeleteProgram(program);
	}
	
	public int getUniformLocation(String str) {
		return glGetUniformLocation(program, str);
	}
}