Learning FBO

[CaptainJester]

I am trying to learn FBOs so I can render to a texture.  It sort of works, but there is a lot of color bleeding between the background and the texture.  If anyone can give me a hint or a solution I would appreciate it.  Here is the code.

The only 2 methods that have FBO code are initGL and render.

package lesson;
/*
 *      This Code Was Created By Jeff Molofee 2000
 *      A HUGE Thanks To Fredric Echols For Cleaning Up
 *      And Optimizing The Base Code, Making It More Flexible!
 *      If You've Found This Code Useful, Please Let Me Know.
 *      Visit My Site At nehe.gamedev.net
 */


import java.awt.image.BufferedImage;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.IntBuffer;

import javax.imageio.ImageIO;

import org.lwjgl.opengl.Display;
import org.lwjgl.opengl.DisplayMode;
import org.lwjgl.opengl.EXTFramebufferObject;
import org.lwjgl.opengl.GL11;
import org.lwjgl.util.glu.GLU;
import org.lwjgl.input.Keyboard;

/**
 * @author Mark Bernard
 * date:    16-Nov-2003
 *
 * Port of NeHe's Lesson 6 to LWJGL
 * Title: Texture Mapping
 * Uses version 0.8alpha of LWJGL http://www.lwjgl.org/
 *
 * Be sure that the LWJGL libraries are in your classpath
 *
 * Ported directly from the C++ version
 *
 * 2004-05-08: Updated to version 0.9alpha of LWJGL.
 *             Changed from all static to all instance objects.
 * 2004-09-21: Updated to version 0.92alpha of LWJGL.
 * 2004-12-17: Updated to version 0.94alpha of LWJGL and to use
 *             DevIL for image loading.
 */
public class Lesson06 {
    private boolean done = false;
    private boolean fullscreen = false;
    private final String windowTitle = "NeHe's OpenGL Lesson 6 for LWJGL (Texture Mapping)";
    private boolean f1 = false;
    private DisplayMode displayMode;

    private float xrot;            // X Rotation ( NEW )
    private float yrot;            // Y Rotation ( NEW )
    private float zrot;            // Z Rotation ( NEW )
    private int texture;           // Storage For One Texture ( NEW )
    private int frameBufferId;

    public static void main(String args[]) {
        boolean fullscreen = false;
        if(args.length>0) {
            if(args[0].equalsIgnoreCase("fullscreen")) {
                fullscreen = true;
            }
        }

        Lesson06 l6 = new Lesson06();
        l6.run(fullscreen);
    }
    public void run(boolean fullscreen) {
        this.fullscreen = fullscreen;
        try {
            init();
            while (!done) {
                mainloop();
                render();
                Display.update();
            }
            cleanup();
        }
        catch (Exception e) {
            e.printStackTrace();
            System.exit(0);
        }
    }
    private void mainloop() {
        if(Keyboard.isKeyDown(Keyboard.KEY_ESCAPE)) {       // Exit if Escape is pressed
            done = true;
        }
        if(Display.isCloseRequested()) {                     // Exit if window is closed
            done = true;
        }
        if(Keyboard.isKeyDown(Keyboard.KEY_F1) && !f1) {    // Is F1 Being Pressed?
            f1 = true;                                      // Tell Program F1 Is Being Held
            switchMode();                                   // Toggle Fullscreen / Windowed Mode
        }
        if(!Keyboard.isKeyDown(Keyboard.KEY_F1)) {          // Is F1 Being Pressed?
            f1 = false;
        }
    }

    private void switchMode() {
        fullscreen = !fullscreen;
        try {
            Display.setFullscreen(fullscreen);
        }
        catch(Exception e) {
            e.printStackTrace();
        }
    }

    private boolean render() {
        GL11.glBindTexture(GL11.GL_TEXTURE_2D, 0);
        EXTFramebufferObject.glBindFramebufferEXT( EXTFramebufferObject.GL_FRAMEBUFFER_EXT, frameBufferId);
        GL11.glPushAttrib(GL11.GL_PIXEL_MODE_BIT);
        GL11.glViewport( 0, 0, 256, 256);
        GL11.glClearColor(0, 0, 0, 0);
        GL11.glClear(GL11.GL_COLOR_BUFFER_BIT | GL11.GL_DEPTH_BUFFER_BIT); // Clear The Screen And The Depth Buffer
        GL11.glColor3d(1.0, 1.0, 1.0);
        GL11.glBegin(GL11.GL_QUADS);
        GL11.glVertex2i(0, 0);
        GL11.glVertex2i(256, 0);
        GL11.glVertex2i(256, 256);
        GL11.glVertex2i(0, 256);
        GL11.glEnd();
        EXTFramebufferObject.glBindFramebufferEXT( EXTFramebufferObject.GL_FRAMEBUFFER_EXT, 0);
        GL11.glBindTexture(GL11.GL_TEXTURE_2D, texture); // Select Our Texture
        EXTFramebufferObject.glGenerateMipmapEXT(GL11.GL_TEXTURE_2D);
        GL11.glBindTexture(GL11.GL_TEXTURE_2D, 0);
        GL11.glPopAttrib();

        GL11.glClearColor(0, 1, 1, 1);
        GL11.glClear(GL11.GL_COLOR_BUFFER_BIT); // Clear The Screen And The Depth Buffer
        GL11.glLoadIdentity(); // Reset The Current Modelview Matrix

        GL11.glTranslatef(0.0f, 0.0f, -5.0f); // Move Into The Screen 5 Units
        GL11.glRotatef(xrot, 1.0f, 0.0f, 0.0f); // Rotate On The X Axis
        GL11.glRotatef(yrot, 0.0f, 1.0f, 0.0f); // Rotate On The Y Axis
        GL11.glRotatef(zrot, 0.0f, 0.0f, 1.0f); // Rotate On The Z Axis
        GL11.glBindTexture(GL11.GL_TEXTURE_2D, texture); // Select Our Texture
        GL11.glBegin(GL11.GL_QUADS);
        // Front Face
        GL11.glTexCoord2f(0.0f, 0.0f);
        GL11.glVertex3f(-1.0f, -1.0f, 1.0f); // Bottom Left Of The Texture and Quad
        GL11.glTexCoord2f(1.0f, 0.0f);
        GL11.glVertex3f(1.0f, -1.0f, 1.0f); // Bottom Right Of The Texture and Quad
        GL11.glTexCoord2f(1.0f, 1.0f);
        GL11.glVertex3f(1.0f, 1.0f, 1.0f); // Top Right Of The Texture and Quad
        GL11.glTexCoord2f(0.0f, 1.0f);
        GL11.glVertex3f(-1.0f, 1.0f, 1.0f); // Top Left Of The Texture and Quad
        // Back Face
        GL11.glTexCoord2f(1.0f, 0.0f);
        GL11.glVertex3f(-1.0f, -1.0f, -1.0f); // Bottom Right Of The Texture and Quad
        GL11.glTexCoord2f(1.0f, 1.0f);
        GL11.glVertex3f(-1.0f, 1.0f, -1.0f); // Top Right Of The Texture and Quad
        GL11.glTexCoord2f(0.0f, 1.0f);
        GL11.glVertex3f(1.0f, 1.0f, -1.0f); // Top Left Of The Texture and Quad
        GL11.glTexCoord2f(0.0f, 0.0f);
        GL11.glVertex3f(1.0f, -1.0f, -1.0f); // Bottom Left Of The Texture and Quad
        // Top Face
        GL11.glTexCoord2f(0.0f, 1.0f);
        GL11.glVertex3f(-1.0f, 1.0f, -1.0f); // Top Left Of The Texture and Quad
        GL11.glTexCoord2f(0.0f, 0.0f);
        GL11.glVertex3f(-1.0f, 1.0f, 1.0f); // Bottom Left Of The Texture and Quad
        GL11.glTexCoord2f(1.0f, 0.0f);
        GL11.glVertex3f(1.0f, 1.0f, 1.0f); // Bottom Right Of The Texture and Quad
        GL11.glTexCoord2f(1.0f, 1.0f);
        GL11.glVertex3f(1.0f, 1.0f, -1.0f); // Top Right Of The Texture and Quad
        // Bottom Face
        GL11.glTexCoord2f(1.0f, 1.0f);
        GL11.glVertex3f(-1.0f, -1.0f, -1.0f); // Top Right Of The Texture and Quad
        GL11.glTexCoord2f(0.0f, 1.0f);
        GL11.glVertex3f(1.0f, -1.0f, -1.0f); // Top Left Of The Texture and Quad
        GL11.glTexCoord2f(0.0f, 0.0f);
        GL11.glVertex3f(1.0f, -1.0f, 1.0f); // Bottom Left Of The Texture and Quad
        GL11.glTexCoord2f(1.0f, 0.0f);
        GL11.glVertex3f(-1.0f, -1.0f, 1.0f); // Bottom Right Of The Texture and Quad
        // Right face
        GL11.glTexCoord2f(1.0f, 0.0f);
        GL11.glVertex3f(1.0f, -1.0f, -1.0f); // Bottom Right Of The Texture and Quad
        GL11.glTexCoord2f(1.0f, 1.0f);
        GL11.glVertex3f(1.0f, 1.0f, -1.0f); // Top Right Of The Texture and Quad
        GL11.glTexCoord2f(0.0f, 1.0f);
        GL11.glVertex3f(1.0f, 1.0f, 1.0f); // Top Left Of The Texture and Quad
        GL11.glTexCoord2f(0.0f, 0.0f);
        GL11.glVertex3f(1.0f, -1.0f, 1.0f); // Bottom Left Of The Texture and Quad
        // Left Face
        GL11.glTexCoord2f(0.0f, 0.0f);
        GL11.glVertex3f(-1.0f, -1.0f, -1.0f); // Bottom Left Of The Texture and Quad
        GL11.glTexCoord2f(1.0f, 0.0f);
        GL11.glVertex3f(-1.0f, -1.0f, 1.0f); // Bottom Right Of The Texture and Quad
        GL11.glTexCoord2f(1.0f, 1.0f);
        GL11.glVertex3f(-1.0f, 1.0f, 1.0f); // Top Right Of The Texture and Quad
        GL11.glTexCoord2f(0.0f, 1.0f);
        GL11.glVertex3f(-1.0f, 1.0f, -1.0f); // Top Left Of The Texture and Quad
        GL11.glEnd();

        xrot += 0.3f; // X Axis Rotation
        yrot += 0.2f; // Y Axis Rotation
        zrot += 0.4f; // Z Axis Rotation

        return true;
    }
    private void createWindow() throws Exception {
        Display.setFullscreen(fullscreen);
        DisplayMode d[] = Display.getAvailableDisplayModes();
        for (int i = 0; i < d.length; i++) {
            if (d[i].getWidth() == 640
                && d[i].getHeight() == 480
                && d[i].getBitsPerPixel() == 32) {
                displayMode = d[i];
                break;
            }
        }
        Display.setDisplayMode(displayMode);
        Display.setTitle(windowTitle);
        Display.create();
    }

    private void init() throws Exception {
        createWindow();

        loadTextures();
        initGL();
    }

    private void loadTextures() throws IOException {
        texture = loadTexture("data/NeHe.bmp");
    }

    private void initGL() {
        GL11.glEnable(GL11.GL_TEXTURE_2D); // Enable Texture Mapping
        GL11.glShadeModel(GL11.GL_SMOOTH); // Enable Smooth Shading
        GL11.glClearColor(0.0f, 0.0f, 0.0f, 0.0f); // Black Background
        GL11.glClearDepth(1.0f); // Depth Buffer Setup
        GL11.glEnable(GL11.GL_DEPTH_TEST); // Enables Depth Testing
        GL11.glDepthFunc(GL11.GL_LEQUAL); // The Type Of Depth Testing To Do

        GL11.glMatrixMode(GL11.GL_PROJECTION); // Select The Projection Matrix
        GL11.glLoadIdentity(); // Reset The Projection Matrix

        // Calculate The Aspect Ratio Of The Window
        GLU.gluPerspective(45.0f, (float) displayMode.getWidth() / (float) displayMode.getHeight(), 0.1f, 100.0f);
        GL11.glMatrixMode(GL11.GL_MODELVIEW); // Select The Modelview Matrix

        // Really Nice Perspective Calculations
        GL11.glHint(GL11.GL_PERSPECTIVE_CORRECTION_HINT, GL11.GL_NICEST);
        
        IntBuffer fboId = ByteBuffer.allocateDirect(4).asIntBuffer();
        EXTFramebufferObject.glGenFramebuffersEXT(fboId);
        frameBufferId = fboId.get();
        EXTFramebufferObject.glBindFramebufferEXT(EXTFramebufferObject.GL_FRAMEBUFFER_EXT, frameBufferId);
        EXTFramebufferObject.glFramebufferTexture2DEXT(EXTFramebufferObject.GL_FRAMEBUFFER_EXT, EXTFramebufferObject.GL_COLOR_ATTACHMENT0_EXT, GL11.GL_TEXTURE_2D, texture, 0);
        int framebuffer = EXTFramebufferObject.glCheckFramebufferStatusEXT( EXTFramebufferObject.GL_FRAMEBUFFER_EXT ); 
        switch ( framebuffer ) {
            case EXTFramebufferObject.GL_FRAMEBUFFER_COMPLETE_EXT:
                break;
            case EXTFramebufferObject.GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT_EXT:
                throw new RuntimeException( "FrameBuffer: " + frameBufferId
                        + ", has caused a GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT_EXT exception" );
            case EXTFramebufferObject.GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT_EXT:
                throw new RuntimeException( "FrameBuffer: " + frameBufferId
                        + ", has caused a GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT_EXT exception" );
            case EXTFramebufferObject.GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS_EXT:
                throw new RuntimeException( "FrameBuffer: " + frameBufferId
                        + ", has caused a GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS_EXT exception" );
            case EXTFramebufferObject.GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER_EXT:
                throw new RuntimeException( "FrameBuffer: " + frameBufferId
                        + ", has caused a GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER_EXT exception" );
            case EXTFramebufferObject.GL_FRAMEBUFFER_INCOMPLETE_FORMATS_EXT:
                throw new RuntimeException( "FrameBuffer: " + frameBufferId
                        + ", has caused a GL_FRAMEBUFFER_INCOMPLETE_FORMATS_EXT exception" );
            case EXTFramebufferObject.GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER_EXT:
                throw new RuntimeException( "FrameBuffer: " + frameBufferId
                        + ", has caused a GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER_EXT exception" );
            default:
                throw new RuntimeException( "Unexpected reply from glCheckFramebufferStatusEXT: " + framebuffer );
        }
        EXTFramebufferObject.glBindFramebufferEXT(EXTFramebufferObject.GL_FRAMEBUFFER_EXT, 0);
    }
    private void cleanup() {
        Display.destroy();
    }
    /**
     * Texture loading using DevIL
     * Example created by Mark Bernard
     */
    private int loadTexture(String path) throws IOException {
        BufferedImage image = ImageIO.read(getClass().getResourceAsStream("data/NeHe.bmp"));
        byte data[] = (byte[])image.getRaster().getDataElements(0, 0, image.getWidth(), image.getHeight(), null);
        ByteBuffer scratch = ByteBuffer.allocateDirect(image.getWidth() * image.getHeight() * 3).order(ByteOrder.nativeOrder());
        scratch.put(data);
        scratch.rewind();
        
        // Create A IntBuffer For Image Address In Memory
        IntBuffer buf = ByteBuffer.allocateDirect(4).order(ByteOrder.nativeOrder()).asIntBuffer();
        GL11.glGenTextures(buf); // Create Texture In OpenGL

        GL11.glBindTexture(GL11.GL_TEXTURE_2D, buf.get(0));
        // Typical Texture Generation Using Data From The Image

        // Linear Filtering
        GL11.glTexParameteri(GL11.GL_TEXTURE_2D, GL11.GL_TEXTURE_MIN_FILTER, GL11.GL_LINEAR);
        // Linear Filtering
        GL11.glTexParameteri(GL11.GL_TEXTURE_2D, GL11.GL_TEXTURE_MAG_FILTER, GL11.GL_LINEAR);
        // Generate The Texture
        GL11.glTexImage2D(GL11.GL_TEXTURE_2D, 0, GL11.GL_RGB, image.getWidth(), 
                image.getHeight(), 0, GL11.GL_RGB, GL11.GL_UNSIGNED_BYTE, scratch);

        return buf.get(0); // Return Image Address In Memory
    }
}

[bobjob]

I attached an FBO example to another post here a while ago

[CaptainJester]

Great, thanks.  I'll take a look.

I tried a search before but there were so many results I couldn't find it.