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TestScreenshot.java
Java
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package mdesl.test;
 
import static org.lwjgl.opengl.GL11.GL_COLOR_BUFFER_BIT;
import static org.lwjgl.opengl.GL11.GL_ONE;
import static org.lwjgl.opengl.GL11.GL_ONE_MINUS_SRC_ALPHA;
import static org.lwjgl.opengl.GL11.GL_RGBA;
import static org.lwjgl.opengl.GL11.GL_SRC_ALPHA;
import static org.lwjgl.opengl.GL11.GL_TEXTURE_2D;
import static org.lwjgl.opengl.GL11.GL_UNSIGNED_BYTE;
import static org.lwjgl.opengl.GL11.glBlendFunc;
import static org.lwjgl.opengl.GL11.glClear;
import static org.lwjgl.opengl.GL11.glClearColor;
import static org.lwjgl.opengl.GL11.glGetTexImage;
 
import java.awt.image.BufferedImage;
import java.awt.image.DataBufferInt;
import java.io.File;
import java.io.IOException;
import java.nio.ByteBuffer;
 
import javax.imageio.ImageIO;
 
import mdesl.graphics.SpriteBatch;
import mdesl.graphics.Texture;
import mdesl.graphics.glutils.FrameBuffer;
 
import org.lwjgl.BufferUtils;
import org.lwjgl.LWJGLException;
import org.lwjgl.Sys;
import org.lwjgl.input.Mouse;
import org.lwjgl.opengl.Display;
 
public class TestScreenshot extends SimpleGame {
 
SpriteBatch batch;
Texture tex0, tex1;
boolean firstRun = true;
FrameBuffer fbo;
public void create() throws LWJGLException {
super.create();
batch = new SpriteBatch();
fbo = new FrameBuffer(128, 128);
try {
tex0 = new Texture(Util.getResource("res/particle.png"));
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
Sys.alert("Error", "Could not load images");
System.exit(0);
}
}
public void render() throws LWJGLException {
glClearColor(0f, 0f, 0f, 0f);
glClear(GL_COLOR_BUFFER_BIT);
fbo.begin();
//clear FBO
glClearColor(0f, 0f, 0f, 0f);
glClear(GL_COLOR_BUFFER_BIT);
boolean additive = Mouse.isButtonDown(0);
//setup FBO blend func
glBlendFunc(GL_ONE, additive ? GL_ONE : GL_ONE_MINUS_SRC_ALPHA);
//resize FBO
batch.resize(fbo.getWidth(), fbo.getHeight());
//draw all our particles
batch.begin();
batch.draw(tex0, 0, 0);
batch.draw(tex0, 21, 0);
batch.end();
fbo.end();
//apply regular blending
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
batch.resize(Display.getWidth(), Display.getHeight());
batch.begin();
batch.draw(fbo, 0, 0);
batch.end();
//take a "snap shot" of the first frame
if (firstRun) {
firstRun = false;
try {
ImageIO.write(getFBOImage(), "PNG", new File("test.png"));
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
//load image back in...
try {
tex1 = new Texture(new File("test.png").toURI().toURL());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
Sys.alert("Error", "Could not load images");
System.exit(0);
}
}
//rendering the image back with regular blending...
batch.begin();
batch.draw(tex1, tex1.getWidth()+10, 0);
batch.end();
}
public BufferedImage getFBOImage() {
int width = fbo.getWidth();
int height = fbo.getHeight();
ByteBuffer buffer = BufferUtils.createByteBuffer(width * height * 4);
glGetTexImage(GL_TEXTURE_2D, 0, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
int[] px = ((DataBufferInt)image.getRaster().getDataBuffer()).getData();
for (int x = 0; x < width; x++) {
for (int y = 0; y < height; y++) {
int i = (x + (width * y)) * 4;
int r = buffer.get(i) & 0xff;
int g = buffer.get(i + 1) & 0xff;
int b = buffer.get(i + 2) & 0xff;
int a = buffer.get(i + 3) & 0xff;
int argb = (a<<24) | (r<<16) | (g<<8) | b;
int off = (x + width * (height-y-1));
px[off] = argb;
}
}
return image;
}
public static void main(String[] args) throws LWJGLException {
Game game = new TestScreenshot();
game.setDisplayMode(800, 600, false);
game.start();
}
}

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