ShaderHelper.java

/**
 * Original class written by Vazkii for Botania.
 */

// TEMA: this is the main shader stuff, where the programs are loaded and compiled for the card.
// other relevant files are the shader in /assets/physis/shader/, and the tesr in /client/render/tile/
// they have other comments like this in.

package ttftcuts.physis.common.helper;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;

import net.minecraft.client.renderer.OpenGlHelper;

import org.lwjgl.opengl.ARBFragmentShader;
import org.lwjgl.opengl.ARBShaderObjects;
import org.lwjgl.opengl.ARBVertexShader;
import org.lwjgl.opengl.GL11;

import ttftcuts.physis.Physis;
import ttftcuts.physis.common.handler.ClientTickHandler;

public final class ShaderHelper {
	private static final int VERT = ARBVertexShader.GL_VERTEX_SHADER_ARB;
	private static final int FRAG = ARBFragmentShader.GL_FRAGMENT_SHADER_ARB;
	private static final String PREFIX = "/assets/physis/shader/";

	public static int testShader = 0;

	public static void initShaders() {
		if(!useShaders())
			return;
		
		testShader = createProgram("test2.vert", "test2.frag");
	}

	public static void useShader(int shader, ShaderCallback callback) {
		if(!useShaders())
			return;

		ARBShaderObjects.glUseProgramObjectARB(shader);

		if(shader != 0) {
			int time = ARBShaderObjects.glGetUniformLocationARB(shader, "time");
			ARBShaderObjects.glUniform1iARB(time, ClientTickHandler.gameTicks);

			if(callback != null)
				callback.call(shader);
		}
	}

	public static void useShader(int shader) {
		useShader(shader, null);
	}

	public static void releaseShader() {
		useShader(0);
	}

	public static boolean useShaders() {
		// TEMA: here's where you'd stick in any config option for enabling/disabling the shaders... don't know how it would interact with the shader mod, etc.
		
		//return ConfigHandler.useShaders && OpenGlHelper.shadersSupported;
		return OpenGlHelper.shadersSupported;
	}

	// Most of the code taken from the LWJGL wiki
	// http://lwjgl.org/wiki/index.php?title=GLSL_Shaders_with_LWJGL

	private static int createProgram(String vert, String frag) {
		int vertId = 0, fragId = 0, program = 0;
		if(vert != null)
			vertId = createShader(PREFIX + vert, VERT);
		if(frag != null)
			fragId = createShader(PREFIX + frag, FRAG);

		program = ARBShaderObjects.glCreateProgramObjectARB();
		if(program == 0)
			return 0;

		if(vert != null)
			ARBShaderObjects.glAttachObjectARB(program, vertId);
		if(frag != null)
			ARBShaderObjects.glAttachObjectARB(program, fragId);

		ARBShaderObjects.glLinkProgramARB(program);
		if(ARBShaderObjects.glGetObjectParameteriARB(program, ARBShaderObjects.GL_OBJECT_LINK_STATUS_ARB) == GL11.GL_FALSE) {
			Physis.logger.error(getLogInfo(program));
			return 0;
		}

		ARBShaderObjects.glValidateProgramARB(program);
		if (ARBShaderObjects.glGetObjectParameteriARB(program, ARBShaderObjects.GL_OBJECT_VALIDATE_STATUS_ARB) == GL11.GL_FALSE) {
			Physis.logger.error(getLogInfo(program));
			return 0;
		}

		return program;
	}

	private static int createShader(String filename, int shaderType){
		int shader = 0;
		try {
			shader = ARBShaderObjects.glCreateShaderObjectARB(shaderType);

			if(shader == 0)
				return 0;

			ARBShaderObjects.glShaderSourceARB(shader, readFileAsString(filename));
			ARBShaderObjects.glCompileShaderARB(shader);

			if (ARBShaderObjects.glGetObjectParameteriARB(shader, ARBShaderObjects.GL_OBJECT_COMPILE_STATUS_ARB) == GL11.GL_FALSE)
				throw new RuntimeException("Error creating shader: " + getLogInfo(shader));

			return shader;
		}
		catch(Exception e) {
			ARBShaderObjects.glDeleteObjectARB(shader);
			e.printStackTrace();
			return -1;
		}
	}

	private static String getLogInfo(int obj) {
		return ARBShaderObjects.glGetInfoLogARB(obj, ARBShaderObjects.glGetObjectParameteriARB(obj, ARBShaderObjects.GL_OBJECT_INFO_LOG_LENGTH_ARB));
	}

	private static String readFileAsString(String filename) throws Exception {
		StringBuilder source = new StringBuilder();
		InputStream in = ShaderHelper.class.getResourceAsStream(filename);
		Exception exception = null;
		BufferedReader reader;

		if(in == null)
			return "";

		try {
			reader = new BufferedReader(new InputStreamReader(in, "UTF-8"));

			Exception innerExc= null;
			try {
				String line;
				while((line = reader.readLine()) != null)
					source.append(line).append('\n');
			} catch(Exception exc) {
				exception = exc;
			} finally {
				try {
					reader.close();
				} catch(Exception exc) {
					if(innerExc == null)
						innerExc = exc;
					else exc.printStackTrace();
				}
			}

			if(innerExc != null)
				throw innerExc;
		} catch(Exception exc) {
			exception = exc;
		} finally {
			try {
				in.close();
			} catch(Exception exc) {
				if(exception == null)
					exception = exc;
				else exc.printStackTrace();
			}

			if(exception != null)
				throw exception;
		}

		return source.toString();
	}
}