Transparent PNG n'est pas transparent dans LWJGL

Question

J'ai un PNG avec un fond transparent, et j'essaye de l'afficher en utilisant LWJGL. Mais au lieu d'un fond transparent, il apparaît avec un fond noir opaque. Je suis le code de l'exemple "Space Invaders".

Voici mon code. Je m'excuse pour sa longueur, mais je n'ai pas pu le réduire davantage et montrer le graphique. "ball.png" est une image de 256x256 avec un arrière-plan transparent.

package com.ziroby.kata.bouncingBalls; 

import static org.lwjgl.opengl.GL11.*; 
import org.lwjgl.opengl.Display; 

import java.awt.*; 
import java.awt.color.ColorSpace; 
import java.awt.image.*; 
import java.io.IOException; 
import java.net.URL; 
import java.nio.ByteBuffer; 
import java.nio.ByteOrder; 
import java.util.Hashtable; 
import javax.swing.ImageIcon; 

public class Game { 

public void start() throws Exception { 
    Display.setInitialBackground(0.5f, 0.5f, 0.5f); 
    Display.create(); 

    // enable textures since we're going to use these for our sprites 
    glEnable(GL_TEXTURE_2D); 

    glMatrixMode(GL_PROJECTION); 

    glOrtho(0, 800, 600, 0, -1, 1); 
    glMatrixMode(GL_MODELVIEW); 

    getTexture("ball.png"); 

    // clear screen 
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 

    // translate to the right location and prepare to draw 
    glTranslatef(300, 200, 0); 

    // draw a quad textured to match the sprite 
    glBegin(GL_QUADS); 
    { 
     glTexCoord2f(0, 0); 
     glVertex2f(0, 0); 

     glTexCoord2f(0, 1); 
     glVertex2f(0, 100); 

     glTexCoord2f(1, 1); 
     glVertex2f(100, 100); 

     glTexCoord2f(1, 0); 
     glVertex2f(100, 0); 
    } 
    glEnd(); 

    // update window contents 
    Display.update(); 
    Thread.sleep(1000); 

    Display.destroy(); 
} 

public void getTexture(String resourceName) throws IOException { 
    glBindTexture(GL_TEXTURE_2D, 1); 

    BufferedImage bufferedImage = loadImage(resourceName); 
    ByteBuffer textureBuffer = convertImageData(bufferedImage); 
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); 
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); 

    // produce a texture from the byte buffer 
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, bufferedImage.getWidth(), 
      bufferedImage.getHeight(), 0, GL_RGBA, GL_UNSIGNED_BYTE, 
      textureBuffer); 
} 

/** 
* Convert the buffered image to a texture 
*/ 
private ByteBuffer convertImageData(BufferedImage bufferedImage) { 
    ByteBuffer imageBuffer; 
    WritableRaster raster; 
    BufferedImage texImage; 

    ColorModel glAlphaColorModel = new ComponentColorModel(ColorSpace 
      .getInstance(ColorSpace.CS_sRGB), new int[] { 8, 8, 8, 8 }, 
      true, false, Transparency.TRANSLUCENT, DataBuffer.TYPE_BYTE); 

    raster = Raster.createInterleavedRaster(DataBuffer.TYPE_BYTE, 
      bufferedImage.getWidth(), bufferedImage.getHeight(), 4, null); 
    texImage = new BufferedImage(glAlphaColorModel, raster, true, 
      new Hashtable()); 

    // copy the source image into the produced image 
    Graphics g = texImage.getGraphics(); 
    g.setColor(new Color(0f, 0f, 0f, 0f)); 
    g.fillRect(0, 0, 256, 256); 
    g.drawImage(bufferedImage, 0, 0, null); 

    // build a byte buffer from the temporary image 
    // that be used by OpenGL to produce a texture. 
    byte[] data = ((DataBufferByte) texImage.getRaster().getDataBuffer()) 
      .getData(); 

    imageBuffer = ByteBuffer.allocateDirect(data.length); 
    imageBuffer.order(ByteOrder.nativeOrder()); 
    imageBuffer.put(data, 0, data.length); 
    imageBuffer.flip(); 

    return imageBuffer; 
} 

/** 
* Load a given resource as a buffered image 
*/ 
private BufferedImage loadImage(String ref) throws IOException { 
    URL url = getClass().getClassLoader().getResource(ref); 

    // due to an issue with ImageIO and mixed signed code 
    // we are now using good oldfashioned ImageIcon to load 
    // images and the paint it on top of a new BufferedImage 
    Image img = new ImageIcon(url).getImage(); 
    BufferedImage bufferedImage = new BufferedImage(img.getWidth(null), img 
      .getHeight(null), BufferedImage.TYPE_INT_ARGB); 
    Graphics g = bufferedImage.getGraphics(); 
    g.drawImage(img, 0, 0, null); 
    g.dispose(); 

    return bufferedImage; 
} 
} 

Answer 1

Vous devez activer la fusion pour autoriser les bits transparents sur une image lors de l'utilisation d'OpenGL.

Vous aurez besoin d'ajouter quelque chose comme ce qui suit à votre code:

glEnable (GL_BLEND); glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);