net.neilcsmith.praxis.video.opengl.internal.ShaderProgram.java Source code

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/*******************************************************************************
 * 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 net.neilcsmith.praxis.video.opengl.internal;

import net.neilcsmith.praxis.video.opengl.internal.Disposable;
import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import java.nio.IntBuffer;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import net.neilcsmith.praxis.video.opengl.internal.GLContext;
import org.lwjgl.BufferUtils;
import org.lwjgl.opengl.GL20;
import org.lwjgl.opengl.GL21;

//import com.badlogic.gdx.Application;
//import com.badlogic.gdx.Gdx;
//import com.badlogic.gdx.graphics.GL20;
//import com.badlogic.gdx.graphics.Mesh;
//import com.badlogic.gdx.math.Matrix3;
//import com.badlogic.gdx.math.Matrix4;
//import com.badlogic.gdx.utils.BufferUtils;
//import com.badlogic.gdx.utils.Disposable;
//import com.badlogic.gdx.utils.ObjectMap;

/** <p>
 * A shader program encapsulates a vertex and fragment shader pair linked to form a shader program useable with OpenGL ES 2.0.
 * </p>
 * 
 * <p>
 * After construction a ShaderProgram can be used to draw {@link Mesh}. To make the GPU use a specific ShaderProgram the programs
 * {@link ShaderProgram#begin()} method must be used which effectively binds the program.
 * </p>
 * 
 * <p>
 * When a ShaderProgram is bound one can set uniforms, vertex attributes and attributes as needed via the respective methods.
 * </p>
 * 
 * <p>
 * A ShaderProgram can be unbound with a call to {@link ShaderProgram#end()}
 * </p>
 * 
 * <p>
 * A ShaderProgram must be disposed via a call to {@link ShaderProgram#dispose()} when it is no longer needed
 * </p>
 * 
 * <p>
 * ShaderPrograms are managed. In case the OpenGL context is lost all shaders get invalidated and have to be reloaded. This
 * happens on Android when a user switches to another application or receives an incoming call. Managed ShaderPrograms are
 * automatically reloaded when the OpenGL context is recreated so you don't have to do this manually.
 * </p>
 * 
 * @author mzechner */
public class ShaderProgram implements Disposable {
    /** default name for position attributes **/
    public static final String POSITION_ATTRIBUTE = "a_position";
    /** default name for normal attribtues **/
    public static final String NORMAL_ATTRIBUTE = "a_normal";
    /** default name for color attributes **/
    public static final String COLOR_ATTRIBUTE = "a_color";
    /** default name for texcoords attributes, append texture unit number **/
    public static final String TEXCOORD_ATTRIBUTE = "a_texCoord";
    /** default name for tangent attribute **/
    public static final String TANGENT_ATTRIBUTE = "a_tangent";
    /** default name for binormal attribute **/
    public static final String BINORMAL_ATTRIBUTE = "a_binormal";

    /** flag indicating whether attributes & uniforms must be present at all times **/
    public static boolean pedantic = true;

    /** the list of currently available shaders **/
    //   private final static Map<Application, List<ShaderProgram>> shaders = new HashMap<Application, List<ShaderProgram>>();

    /** the log **/
    private String log = "";

    /** whether this program compiled succesfully **/
    private boolean isCompiled;

    /** uniform lookup **/
    //   private final ObjectMap<String, Integer> uniforms = new ObjectMap<String, Integer>();
    private final Map<String, Integer> uniforms = new HashMap<String, Integer>();

    /** uniform types **/
    //   private final ObjectMap<String, Integer> uniformTypes = new ObjectMap<String, Integer>();
    private final Map<String, Integer> uniformTypes = new HashMap<String, Integer>();

    /** uniform names **/
    private String[] uniformNames;

    /** attribute lookup **/
    //   private final ObjectMap<String, Integer> attributes = new ObjectMap<String, Integer>();
    private final Map<String, Integer> attributes = new HashMap<String, Integer>();

    /** attribute types **/
    //   private final ObjectMap<String, Integer> attributeTypes = new ObjectMap<String, Integer>();
    private final Map<String, Integer> attributeTypes = new HashMap<String, Integer>();

    /** attribute names **/
    private String[] attributeNames;

    /** program handle **/
    public int program;

    /** vertex shader handle **/
    private int vertexShaderHandle;

    /** fragment shader handle **/
    private int fragmentShaderHandle;

    /** matrix float buffer **/
    private final FloatBuffer matrix;

    /** vertex shader source **/
    private final String vertexShaderSource;

    /** fragment shader source **/
    private final String fragmentShaderSource;

    /** whether this shader was invalidated **/
    private boolean invalidated;

    /** direct buffer for passing float and int uniform arrays **/
    private ByteBuffer buffer = null;
    private FloatBuffer floatBuffer = null;
    private IntBuffer intBuffer = null;

    /** reference count **/
    private int refCount = 0;

    private GLContext context;

    /** Construcs a new JOglShaderProgram and immediatly compiles it.
     * 
     * @param vertexShader the vertex shader
     * @param fragmentShader the fragment shader */

    public ShaderProgram(String vertexShader, String fragmentShader) {
        if (vertexShader == null)
            throw new IllegalArgumentException("vertex shader must not be null");
        if (fragmentShader == null)
            throw new IllegalArgumentException("fragment shader must not be null");

        this.vertexShaderSource = vertexShader;
        this.fragmentShaderSource = fragmentShader;
        //      this.matrix = BufferUtils.newFloatBuffer(16);
        this.matrix = BufferUtils.createFloatBuffer(16);

        //                context = GLContext.getCurrent();

        //                if (context != null) {
        compileShaders(vertexShader, fragmentShader);
        //                }
    }

    /** Loads and compiles the shaders, creates a new program and links the shaders.
     * 
     * @param vertexShader
     * @param fragmentShader */
    private void compileShaders(String vertexShader, String fragmentShader) {
        vertexShaderHandle = loadShader(GL20.GL_VERTEX_SHADER, vertexShader);
        fragmentShaderHandle = loadShader(GL20.GL_FRAGMENT_SHADER, fragmentShader);

        if (vertexShaderHandle == -1 || fragmentShaderHandle == -1) {
            isCompiled = false;
            return;
        }

        program = linkProgram();
        if (program == -1) {
            isCompiled = false;
            return;
        }

        isCompiled = true;
        fetchAttributes();
        fetchUniforms();
    }

    private int loadShader(int type, String source) {
        //      GL20 gl = Gdx.graphics.getGL20();
        ByteBuffer tmp = ByteBuffer.allocateDirect(4);
        tmp.order(ByteOrder.nativeOrder());
        IntBuffer intbuf = tmp.asIntBuffer();

        int shader = GL20.glCreateShader(type);
        if (shader == 0)
            return -1;

        GL20.glShaderSource(shader, source);
        GL20.glCompileShader(shader);
        GL20.glGetShader(shader, GL20.GL_COMPILE_STATUS, intbuf);

        int compiled = intbuf.get(0);
        if (compiled == 0) {
            GL20.glGetShader(shader, GL20.GL_INFO_LOG_LENGTH, intbuf);
            int infoLogLength = intbuf.get(0);
            if (infoLogLength > 1) {
                String infoLog = getShaderInfoLog(shader);
                log += infoLog;
            }
            return -1;
        }

        return shader;
    }

    private String getShaderInfoLog(int shader) {
        ByteBuffer buffer = ByteBuffer.allocateDirect(1024 * 10);
        buffer.order(ByteOrder.nativeOrder());
        ByteBuffer tmp = ByteBuffer.allocateDirect(4);
        tmp.order(ByteOrder.nativeOrder());
        IntBuffer intBuffer = tmp.asIntBuffer();

        GL20.glGetShaderInfoLog(shader, intBuffer, buffer);
        int numBytes = intBuffer.get(0);
        byte[] bytes = new byte[numBytes];
        buffer.get(bytes);
        return new String(bytes);
    }

    private int linkProgram() {
        int program = GL20.glCreateProgram();
        if (program == 0)
            return -1;

        GL20.glAttachShader(program, vertexShaderHandle);
        GL20.glAttachShader(program, fragmentShaderHandle);
        GL20.glLinkProgram(program);

        //      ByteBuffer tmp = ByteBuffer.allocateDirect(4);
        //      tmp.order(ByteOrder.nativeOrder());
        //      IntBuffer intbuf = tmp.asIntBuffer();

        GL20.glGetProgram(program, GL20.GL_LINK_STATUS, intbuf);
        int linked = intbuf.get(0);
        if (linked == 0) {
            return -1;
        }

        return program;
    }

    final IntBuffer intbuf = BufferUtils.createIntBuffer(1);

    /** @return the log info for the shader compilation and program linking stage. The shader needs to be bound for this method to
     *         have an effect. */
    public String getLog() {
        if (isCompiled) {
            GL20.glGetProgram(program, GL20.GL_INFO_LOG_LENGTH, intbuf);
            int infoLogLength = intbuf.get(0);
            if (infoLogLength > 1)
                log = GL20.glGetProgramInfoLog(program, infoLogLength);
            return log;
        } else {
            return log;
        }
    }

    /** @return whether this ShaderProgram compiled successfully. */
    public boolean isCompiled() {
        return isCompiled;
    }

    private int fetchAttributeLocation(String name) {
        Integer location;
        if ((location = attributes.get(name)) == null) {
            location = GL20.glGetAttribLocation(program, name);
            if (location != -1)
                attributes.put(name, location);
        }
        return location;
    }

    private int fetchUniformLocation(String name) {
        Integer location;
        if ((location = uniforms.get(name)) == null) {
            location = GL20.glGetUniformLocation(program, name);
            if (location == -1 && pedantic)
                throw new IllegalArgumentException("no uniform with name '" + name + "' in shader");
            uniforms.put(name, location);
        }
        return location;
    }

    /** Sets the uniform with the given name. Throws an IllegalArgumentException in case it is not called in between a
     * {@link #begin()}/{@link #end()} block.
     * 
     * @param name the name of the uniform
     * @param value the value */
    public void setUniformi(String name, int value) {
        checkContext();
        int location = fetchUniformLocation(name);
        GL20.glUniform1i(location, value);
    }

    /** Sets the uniform with the given name. Throws an IllegalArgumentException in case it is not called in between a
     * {@link #begin()}/{@link #end()} block.
     * 
     * @param name the name of the uniform
     * @param value1 the first value
     * @param value2 the second value */
    public void setUniformi(String name, int value1, int value2) {
        checkContext();
        int location = fetchUniformLocation(name);
        GL20.glUniform2i(location, value1, value2);
    }

    /** Sets the uniform with the given name. Throws an IllegalArgumentException in case it is not called in between a
     * {@link #begin()}/{@link #end()} block.
     * 
     * @param name the name of the uniform
     * @param value1 the first value
     * @param value2 the second value
     * @param value3 the third value */
    public void setUniformi(String name, int value1, int value2, int value3) {
        checkContext();
        int location = fetchUniformLocation(name);
        GL20.glUniform3i(location, value1, value2, value3);
    }

    /** Sets the uniform with the given name. Throws an IllegalArgumentException in case it is not called in between a
     * {@link #begin()}/{@link #end()} block.
     * 
     * @param name the name of the uniform
     * @param value1 the first value
     * @param value2 the second value
     * @param value3 the third value
     * @param value4 the fourth value */
    public void setUniformi(String name, int value1, int value2, int value3, int value4) {
        checkContext();
        int location = fetchUniformLocation(name);
        GL20.glUniform4i(location, value1, value2, value3, value4);
    }

    /** Sets the uniform with the given name. Throws an IllegalArgumentException in case it is not called in between a
     * {@link #begin()}/{@link #end()} block.
     * 
     * @param name the name of the uniform
     * @param value the value */
    public void setUniformf(String name, float value) {
        checkContext();
        int location = fetchUniformLocation(name);
        GL20.glUniform1f(location, value);
    }

    /** Sets the uniform with the given name. Throws an IllegalArgumentException in case it is not called in between a
     * {@link #begin()}/{@link #end()} block.
     * 
     * @param name the name of the uniform
     * @param value1 the first value
     * @param value2 the second value */
    public void setUniformf(String name, float value1, float value2) {
        checkContext();
        int location = fetchUniformLocation(name);
        GL20.glUniform2f(location, value1, value2);
    }

    /** Sets the uniform with the given name. Throws an IllegalArgumentException in case it is not called in between a
     * {@link #begin()}/{@link #end()} block.
     * 
     * @param name the name of the uniform
     * @param value1 the first value
     * @param value2 the second value
     * @param value3 the third value */
    public void setUniformf(String name, float value1, float value2, float value3) {
        checkContext();
        int location = fetchUniformLocation(name);
        GL20.glUniform3f(location, value1, value2, value3);
    }

    /** Sets the uniform with the given name. Throws an IllegalArgumentException in case it is not called in between a
     * {@link #begin()}/{@link #end()} block.
     * 
     * @param name the name of the uniform
     * @param value1 the first value
     * @param value2 the second value
     * @param value3 the third value
     * @param value4 the fourth value */
    public void setUniformf(String name, float value1, float value2, float value3, float value4) {
        checkContext();
        int location = fetchUniformLocation(name);
        GL20.glUniform4f(location, value1, value2, value3, value4);
    }

    public void setUniform1fv(String name, float[] values, int offset, int length) {
        checkContext();
        int location = fetchUniformLocation(name);
        ensureBufferCapacity(length << 2);
        floatBuffer.clear();
        //      BufferUtils.copy(values, floatBuffer, length, offset);
        floatBuffer.put(values, offset, length);
        floatBuffer.rewind();

        //      GL20.glUniform1fv(location, length, floatBuffer);
        GL20.glUniform1(location, floatBuffer);
    }

    public void setUniform2fv(String name, float[] values, int offset, int length) {
        checkContext();
        int location = fetchUniformLocation(name);
        ensureBufferCapacity(length << 2);
        floatBuffer.clear();
        //      BufferUtils.copy(values, floatBuffer, length, offset);
        floatBuffer.put(values, offset, length);
        floatBuffer.rewind();
        //      gl.glUniform2fv(location, length / 2, floatBuffer);
        GL20.glUniform2(location, floatBuffer);
    }

    public void setUniform3fv(String name, float[] values, int offset, int length) {
        checkContext();
        int location = fetchUniformLocation(name);
        ensureBufferCapacity(length << 2);
        floatBuffer.clear();
        //      BufferUtils.copy(values, floatBuffer, length, offset);
        floatBuffer.put(values, offset, length);
        floatBuffer.rewind();
        GL20.glUniform3(location, floatBuffer);
    }

    public void setUniform4fv(String name, float[] values, int offset, int length) {
        checkContext();
        int location = fetchUniformLocation(name);
        ensureBufferCapacity(length << 2);
        floatBuffer.clear();
        //      BufferUtils.copy(values, floatBuffer, length, offset);
        floatBuffer.put(values, offset, length);
        floatBuffer.rewind();
        GL20.glUniform4(location, floatBuffer);
    }

    /** Sets the uniform matrix with the given name. Throws an IllegalArgumentException in case it is not called in between a
     * {@link #begin()}/{@link #end()} block.
     * 
     * @param name the name of the uniform
     * @param matrix the matrix */
    public void setUniformMatrix(String name, Matrix4 matrix) {
        setUniformMatrix(name, matrix, false);
    }

    /** Sets the uniform matrix with the given name. Throws an IllegalArgumentException in case it is not called in between a
     * {@link #begin()}/{@link #end()} block.
     * 
     * @param name the name of the uniform
     * @param matrix the matrix
     * @param transpose whether the matrix shouls be transposed */
    public void setUniformMatrix(String name, Matrix4 matrix, boolean transpose) {
        checkContext();
        int location = fetchUniformLocation(name);
        this.matrix.clear();
        //      BufferUtils.copy(matrix.val, this.matrix, matrix.val.length, 0);
        this.matrix.put(matrix.val);
        this.matrix.rewind();

        GL20.glUniformMatrix4(location, transpose, this.matrix);
    }

    /** Sets the uniform matrix with the given name. Throws an IllegalArgumentException in case it is not called in between a
     * {@link #begin()}/{@link #end()} block.
     * 
     * @param name the name of the uniform
     * @param matrix the matrix */
    public void setUniformMatrix(String name, Matrix3 matrix) {
        setUniformMatrix(name, matrix, false);
    }

    /** Sets the uniform matrix with the given name. Throws an IllegalArgumentException in case it is not called in between a
     * {@link #begin()}/{@link #end()} block.
     * 
     * @param name the name of the uniform
     * @param matrix the matrix
     * @param transpose whether the uniform matrix should be transposed */
    public void setUniformMatrix(String name, Matrix3 matrix, boolean transpose) {
        checkContext();
        int location = fetchUniformLocation(name);
        float[] vals = matrix.getValues();
        this.matrix.clear();
        //      BufferUtils.copy(vals, this.matrix, vals.length, 0);
        this.matrix.put(vals);
        this.matrix.rewind();
        GL20.glUniformMatrix3(location, transpose, this.matrix);
    }

    //   /** Sets the vertex attribute with the given name. Throws an IllegalArgumentException in case it is not called in between a
    //    * {@link #begin()}/{@link #end()} block.
    //    * 
    //    * @param name the attribute name
    //    * @param size the number of components, must be >= 1 and <= 4
    //    * @param type the type, must be one of GL20.GL_BYTE, GL20.GL_UNSIGNED_BYTE, GL20.GL_SHORT,
    //    *           GL20.GL_UNSIGNED_SHORT,GL20.GL_FIXED, or GL20.GL_FLOAT. GL_FIXED will not work on the desktop
    //    * @param normalize whether fixed point data should be normalized. Will not work on the desktop
    //    * @param stride the stride in bytes between successive attributes
    //    * @param buffer the buffer containing the vertex attributes. */
    //   public void setVertexAttribute (String name, int size, int type, boolean normalize, int stride, FloatBuffer buffer) {
    //      checkManaged();
    //      int location = fetchAttributeLocation(name);
    //      GL20.glVertexAttribPointer(location, size, type, normalize, stride, buffer);
    //        NOT IMPLEMENTED
    //   }

    /** Sets the vertex attribute with the given name. Throws an IllegalArgumentException in case it is not called in between a
     * {@link #begin()}/{@link #end()} block.
     * 
     * @param name the attribute name
     * @param size the number of components, must be >= 1 and <= 4
     * @param type the type, must be one of GL20.GL_BYTE, GL20.GL_UNSIGNED_BYTE, GL20.GL_SHORT,
     *           GL20.GL_UNSIGNED_SHORT,GL20.GL_FIXED, or GL20.GL_FLOAT. GL_FIXED will not work on the desktop
     * @param normalize whether fixed point data should be normalized. Will not work on the desktop
     * @param stride the stride in bytes between successive attributes
     * @param offset byte offset into the vertex buffer object bound to GL20.GL_ARRAY_BUFFER. */
    public void setVertexAttribute(String name, int size, int type, boolean normalize, int stride, int offset) {
        checkContext();
        int location = fetchAttributeLocation(name);
        if (location == -1)
            return;
        GL20.glVertexAttribPointer(location, size, type, normalize, stride, offset);
    }

    /** Makes OpenGL ES 2.0 use this vertex and fragment shader pair. When you are done with this shader you have to call
     * {@link ShaderProgram#end()}. */
    public void begin() {
        checkContext();
        GL20.glUseProgram(program);
    }

    /** Disables this shader. Must be called when one is done with the shader. Don't mix it with dispose, that will release the
     * shader resources. */
    public void end() {
        GL20.glUseProgram(0);
    }

    /** Disposes all resources associated with this shader. Must be called when the shader is no longer used. */
    public void dispose() {
        GL20.glUseProgram(0);
        GL20.glDeleteShader(vertexShaderHandle);
        GL20.glDeleteShader(fragmentShaderHandle);
        GL20.glDeleteProgram(program);
        //      if (shaders.get(Gdx.app) != null) shaders.get(Gdx.app).remove(this);
    }

    /** Disables the vertex attribute with the given name
     * 
     * @param name the vertex attribute name */
    public void disableVertexAttribute(String name) {
        checkContext();
        int location = fetchAttributeLocation(name);
        if (location == -1)
            return;
        GL20.glDisableVertexAttribArray(location);
    }

    /** Enables the vertex attribute with the given name
     * 
     * @param name the vertex attribute name */
    public void enableVertexAttribute(String name) {
        checkContext();
        int location = fetchAttributeLocation(name);
        if (location == -1)
            return;
        GL20.glEnableVertexAttribArray(location);
    }

    private void checkContext() {
        GLContext ctxt = GLContext.getCurrent();
        if (ctxt != context) {
            compileShaders(vertexShaderSource, fragmentShaderSource);
            context = ctxt;
        }
    }

    //   private void addManagedShader (Application app, ShaderProgram shaderProgram) {
    //      List<ShaderProgram> managedResources = shaders.get(app);
    //      if (managedResources == null) managedResources = new ArrayList<ShaderProgram>();
    //      managedResources.add(shaderProgram);
    //      shaders.put(app, managedResources);
    //   }

    //   /** Invalidates all shaders so the next time they are used new handles are generated
    //    * @param app */
    //   public static void invalidateAllShaderPrograms (Application app) {
    //      if (Gdx.graphics.getGL20() == null) return;
    //
    //      List<ShaderProgram> shaderList = shaders.get(app);
    //      if (shaderList == null) return;
    //
    //      for (int i = 0; i < shaderList.size(); i++) {
    //         shaderList.get(i).invalidated = true;
    //         shaderList.get(i).checkManaged();
    //      }
    //   }

    //   public static void clearAllShaderPrograms (Application app) {
    //      shaders.remove(app);
    //   }

    //   public static String getManagedStatus () {
    //      StringBuilder builder = new StringBuilder();
    //      int i = 0;
    //      builder.append("Managed shaders/app: { ");
    //      for (Application app : shaders.keySet()) {
    //         builder.append(shaders.get(app).size());
    //         builder.append(" ");
    //      }
    //      builder.append("}");
    //      return builder.toString();
    //   }

    /** Sets the given attribute
     * 
     * @param name the name of the attribute
     * @param value1 the first value
     * @param value2 the second value
     * @param value3 the third value
     * @param value4 the fourth value */
    public void setAttributef(String name, float value1, float value2, float value3, float value4) {
        int location = fetchAttributeLocation(name);
        GL20.glVertexAttrib4f(location, value1, value2, value3, value4);
    }

    private void ensureBufferCapacity(int numBytes) {
        if (buffer == null || buffer.capacity() != numBytes) {
            //         buffer = BufferUtils.newByteBuffer(numBytes);
            buffer = BufferUtils.createByteBuffer(numBytes);
            floatBuffer = buffer.asFloatBuffer();
            intBuffer = buffer.asIntBuffer();
        }
    }

    IntBuffer params = BufferUtils.createIntBuffer(1);
    IntBuffer type = BufferUtils.createIntBuffer(1);

    private void fetchUniforms() {
        params.clear();
        GL20.glGetProgram(program, GL20.GL_ACTIVE_UNIFORMS, params);
        int numUniforms = params.get(0);

        uniformNames = new String[numUniforms];

        for (int i = 0; i < numUniforms; i++) {
            params.clear();
            params.put(0, 256);
            type.clear();
            String name = glGetActiveUniform(program, i, params, type);
            int location = GL20.glGetUniformLocation(program, name);
            uniforms.put(name, location);
            uniformTypes.put(name, type.get(0));
            uniformNames[i] = name;
        }
    }

    private String glGetActiveUniform(int program, int index, IntBuffer size, Buffer type) {
        // FIXME this is less than ideal of course...
        IntBuffer typeTmp = BufferUtils.createIntBuffer(2);
        String name = GL20.glGetActiveUniform(program, index, 256, typeTmp);
        if (type instanceof IntBuffer)
            ((IntBuffer) type).put(typeTmp.get(0));
        return name;
    }

    private void fetchAttributes() {
        params.clear();
        GL20.glGetProgram(program, GL20.GL_ACTIVE_ATTRIBUTES, params);
        int numAttributes = params.get(0);

        attributeNames = new String[numAttributes];

        for (int i = 0; i < numAttributes; i++) {
            params.clear();
            params.put(0, 256);
            type.clear();
            String name = glGetActiveAttrib(program, i, params, type);
            int location = GL20.glGetAttribLocation(program, name);
            attributes.put(name, location);
            attributeTypes.put(name, type.get(0));
            attributeNames[i] = name;
        }
    }

    private String glGetActiveAttrib(int program, int index, IntBuffer size, Buffer type) {
        // FIXME this is less than ideal of course...
        IntBuffer typeTmp = BufferUtils.createIntBuffer(2);
        String name = GL20.glGetActiveAttrib(program, index, 256, typeTmp);
        if (type instanceof IntBuffer)
            ((IntBuffer) type).put(typeTmp.get(0));
        return name;
    }

    /** @param name the name of the attribute
     * @return whether the attribute is available in the shader */
    public boolean hasAttribute(String name) {
        return attributes.containsKey(name);
    }

    /** @param name the name of the attribute
     * @return the type of the attribute, one of {@link GL20#GL_FLOAT}, {@link GL20#GL_FLOAT_VEC2} etc. */
    public int getAttributeType(String name) {
        Integer type = attributes.get(name);
        if (type == null)
            return 0;
        else
            return type;
    }

    /** @param name the name of the attribute
     * @return the location of the attribute or -1. */
    public int getAttributeLocation(String name) {
        Integer location = attributes.get(name);
        if (location == null)
            return -1;
        else
            return location;
    }

    /** @param name the name of the uniform
     * @return whether the uniform is available in the shader */
    public boolean hasUniform(String name) {
        return uniforms.containsKey(name);
    }

    /** @param name the name of the uniform
     * @return the type of the uniform, one of {@link GL20#GL_FLOAT}, {@link GL20#GL_FLOAT_VEC2} etc. */
    public int getUniformType(String name) {
        Integer type = uniformTypes.get(name);
        if (type == null)
            return 0;
        else
            return type;
    }

    /** @param name the name of the uniform
     * @return the location of the uniform or -1. */
    public int getUniformLocation(String name) {
        Integer location = uniforms.get(name);
        if (location == null)
            return -1;
        else
            return location;
    }

    /** @return the attributes */
    public String[] getAttributes() {
        return attributeNames;
    }

    /** @return the uniforms */
    public String[] getUniforms() {
        return uniformNames;
    }
}