java - 在 LWJGL 中渲染到 FBO

Question

我正在尝试使用 Java 将一些基本四边形渲染到 LWJGL 中的 FBO，但它实际上并未渲染，我不知道为什么。

import static org.lwjgl.opengl.GL11.*;
import static org.lwjgl.util.glu.GLU.*;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import java.nio.IntBuffer;

import org.lwjgl.BufferUtils;
import org.lwjgl.LWJGLException;
import org.lwjgl.Sys;
import org.lwjgl.input.Keyboard;
import org.lwjgl.input.Mouse;
import org.lwjgl.opengl.Display;
import org.lwjgl.opengl.DisplayMode;
import org.lwjgl.opengl.EXTFramebufferObject;
import org.lwjgl.opengl.GLContext;
import org.newdawn.slick.Color;

import elec0.utils.Camera;
import elec0.utils.Vector2f;
import elec0.utils.Vector3f;

public class lwjglFBO
{
    private Camera camera = new Camera();
    private boolean running = true, wireframe = false;
    private long lastFPS;
    private int fps;

//  boolean FBOEnabled = GLContext.getCapabilities().GL_EXT_framebuffer_object;
    private int iFBOBuffer;

    public void start()
    {
        initGL();
        init();

        lastFPS = getTime();

        while(!Display.isCloseRequested())
        {
            updateFPS();
            pollInput();


            render();

            Display.update();
            Display.sync(60); // limit FPS to 60
        }
        Display.destroy();
        System.exit(0);
    }

    private void render()
    {
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();

        /*gluLookAt(0, 0, 5, // Set up the LookAt
                0, 0, 0,
                0, 1, 0);*/

        camera.render();

        drawGrid(); // Render this fill, it's lines
        int verts = 0;
        EXTFramebufferObject.glBindFramebufferEXT( EXTFramebufferObject.GL_FRAMEBUFFER_EXT, iFBOBuffer );
        glPushAttrib(GL_VIEWPORT_BIT);
        glViewport( 0, 0, 800, 600);
        glClear(GL_COLOR_BUFFER_BIT);


        for(int z = 0; z < 20; ++z)
        {
            for(int y = 0; y < 20; ++y)
            {
                for(int x = 0; x < 20; ++x)
                {
                    glPushMatrix();
                    glTranslatef(x, y, z);
                    drawBox();
//                  verts+=24;
                    glPopMatrix();
                }
            }
        }
//        System.out.println(verts);

        EXTFramebufferObject.glBindFramebufferEXT( EXTFramebufferObject.GL_FRAMEBUFFER_EXT, 0);
        glPopAttrib();
        // Render
        if(wireframe)
            glPolygonMode( GL_FRONT_AND_BACK, GL_LINE );
        else
            glPolygonMode( GL_FRONT_AND_BACK, GL_FILL );


    }

    private void drawBox()
    {
         /* draws the sides of a unit cube (0,0,0)-(1,1,1) */
          glBegin(GL_POLYGON);/* f1: front */
            glNormal3f(-1.0f,0.0f,0.0f);
            glVertex3f(0.0f,0.0f,0.0f);
            glVertex3f(0.0f,0.0f,1.0f);
            glVertex3f(1.0f,0.0f,1.0f);
            glVertex3f(1.0f,0.0f,0.0f);
          glEnd();
          glBegin(GL_POLYGON);/* f2: bottom */
            glNormal3f(0.0f,0.0f,-1.0f);
            glVertex3f(0.0f,0.0f,0.0f);
            glVertex3f(1.0f,0.0f,0.0f);
            glVertex3f(1.0f,1.0f,0.0f);
            glVertex3f(0.0f,1.0f,0.0f);
          glEnd();
          glBegin(GL_POLYGON);/* f3:back */
            glNormal3f(1.0f,0.0f,0.0f);
            glVertex3f(1.0f,1.0f,0.0f);
            glVertex3f(1.0f,1.0f,1.0f);
            glVertex3f(0.0f,1.0f,1.0f);
            glVertex3f(0.0f,1.0f,0.0f);
          glEnd();
          glBegin(GL_POLYGON);/* f4: top */
            glNormal3f(0.0f,0.0f,1.0f);
            glVertex3f(1.0f,1.0f,1.0f);
            glVertex3f(1.0f,0.0f,1.0f);
            glVertex3f(0.0f,0.0f,1.0f);
            glVertex3f(0.0f,1.0f,1.0f);
          glEnd();
          glBegin(GL_POLYGON);/* f5: left */
            glNormal3f(0.0f,1.0f,0.0f);
            glVertex3f(0.0f,0.0f,0.0f);
            glVertex3f(0.0f,1.0f,0.0f);
            glVertex3f(0.0f,1.0f,1.0f);
            glVertex3f(0.0f,0.0f,1.0f);
          glEnd();
          glBegin(GL_POLYGON);/* f6: right */
            glNormal3f(0.0f,-1.0f,0.0f);
            glVertex3f(1.0f,0.0f,0.0f);
            glVertex3f(1.0f,0.0f,1.0f);
            glVertex3f(1.0f,1.0f,1.0f);
            glVertex3f(1.0f,1.0f,0.0f);
          glEnd();

    }

    private void init()
    {

        Mouse.setGrabbed(true);
        camera.initCamera();
        camera.farPlane = 1000;
        camera.initPerspective();

    }

    private void initGL()
    {   
        try {
            Display.setDisplayMode(new DisplayMode(800, 600));
            Display.create();
            Display.setVSyncEnabled(true);
        } catch (LWJGLException e) {
            e.printStackTrace();
            System.exit(0);
        }

        glViewport(0, 0, Display.getWidth(), Display.getHeight());

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

        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();


        IntBuffer buffer = ByteBuffer.allocateDirect(1*4).order(ByteOrder.nativeOrder()).asIntBuffer(); // allocate a 1 int byte buffer
        EXTFramebufferObject.glGenFramebuffersEXT( buffer ); // generate 
        iFBOBuffer = buffer.get();

//      glEnable(GL_FOG); 
//          FloatBuffer fogColor = BufferUtils.createFloatBuffer(4);
//          fogColor.put(0f).put(0f).put(0f).put(1f).flip();
//          
//          int fogMode = GL_LINEAR;
//          glFogi(GL_FOG_MODE, fogMode);
//          glFog(GL_FOG_COLOR, fogColor);
//          glFogf(GL_FOG_DENSITY, 0.35f);
//          glHint(GL_FOG_HINT, GL_DONT_CARE);
//          glFogf(GL_FOG_START, 100.0f);
//          glFogf(GL_FOG_END, 500.0f);

        // Alpha blending
        glEnable(GL_BLEND);
        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

        glMatrixMode(GL_MODELVIEW); // Select The Modelview Matrix
        glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);



    }

    private long lastF;


    private void pollInput()
    {
        int x = Mouse.getX();
        int y = Display.getHeight() - Mouse.getY();
        float speed = .1f;
        int iKeypressSpeed = 50;
        int iDelta = getDelta();
        speed *= iDelta;

        if(Keyboard.isKeyDown(Keyboard.KEY_LSHIFT))
            speed *= 4;

        if(Keyboard.isKeyDown(Keyboard.KEY_W))
        {
            camera.MoveForwards(speed);
        }
        if(Keyboard.isKeyDown(Keyboard.KEY_S))
        {
            camera.MoveForwards(-speed);
        }
        if(Keyboard.isKeyDown(Keyboard.KEY_A))
        {
            camera.MoveRight(-speed);
        }
        if(Keyboard.isKeyDown(Keyboard.KEY_D))
        {
            camera.MoveRight(speed);
        }
        if(Keyboard.isKeyDown(Keyboard.KEY_SPACE))
        {
            camera.moveUp(speed);
        }

        if(Keyboard.isKeyDown(Keyboard.KEY_ESCAPE))
        {
            Display.destroy();
            System.exit(0);
        }
        if(Keyboard.isKeyDown(Keyboard.KEY_P))
        {
            if(getTime() - lastF > iKeypressSpeed)
                wireframe = !wireframe;
            lastF = getTime();
        }
        if(Keyboard.isKeyDown(Keyboard.KEY_N))
        {
            if(getTime() - lastF > iKeypressSpeed)
            lastF = getTime();
        }
        if(Keyboard.isKeyDown(Keyboard.KEY_C))
        {
            if(getTime() - lastF > iKeypressSpeed)
            lastF = getTime();
        }

        checkMouseMove(x, y);
    }

    Vector2f previous = new Vector2f(), mousePos = new Vector2f();
    private float MOUSE_SENSITIVITY = 4.0f;

    private void checkMouseMove(float x, float y)
    {
        float DeltX, DeltY;
        int centX = Display.getWidth()/2, centY = Display.getHeight()/2;

        DeltX = (float)(centX - x) / MOUSE_SENSITIVITY;
        DeltY = (float)(centY - y) / MOUSE_SENSITIVITY;

        camera.Rotate(DeltY, DeltX, 0);

        Mouse.setCursorPosition(centX, centY);
    }

    public long getTime() 
    {
        return (Sys.getTime() * 1000) / Sys.getTimerResolution();
    }

    public void updateFPS() 
    {
        if (getTime() - lastFPS > 1000) {
            Display.setTitle("FPS: " + fps); 
            fps = 0; //reset the FPS counter
            lastFPS += 1000; //add one second
        }
        fps++;
    }

    long lastFrame;
    public int getDelta() 
    {
        long time = getTime();

        int delta = (int) (time - lastFrame);

        lastFrame = time;   
        return delta;   
    }

    private void drawGrid()
    {       
        glPushMatrix();

        glDisable(GL_TEXTURE_2D);

        glColor3f(0.25f, 0.25f, 0.25f);

        float gridSize = 30;
        int mX = 64, mZ = 64;

        glTranslatef(-(mX+gridSize)/2, -5, -(mZ+gridSize)/2);


        for(int x = 0; x < mX; ++x)
        {
            for(int z = 0; z < mZ; ++z)
            {
                glBegin(GL_LINE_LOOP);
                    glVertex3f(x, 0, z);
                    glVertex3f(x+gridSize, 0, z);
                    glVertex3f(x+gridSize, 0, z+gridSize);
                    glVertex3f(x, 0, z+gridSize);
                glEnd();
            }
        }

        glEnable(GL_TEXTURE_2D);
        glPopMatrix();
    }

    public static void main(String[] args)
    {
        lwjglFBO city = new lwjglFBO();
        city.start();

    }
}

Answer 1

我花了一些时间查看你的代码，我可能只是错过了一些东西，但我找不到你在哪里获取 fbo 纹理并将其渲染在屏幕上的地方。

我看到了你绘制网格的位置以及绘制所有立方体的位置，但我没有看到任何东西绑定(bind)到任何立方体。