LWJGL Forum

Hi there,

i am currently trying to use my own matrix class, but i cant glLoadMatrix to get working.
Here is the code for reproducing this.


package game;

import java.nio.ByteBuffer;
import java.nio.FloatBuffer;

import org.lwjgl.LWJGLException;
import org.lwjgl.opengl.Display;
import org.lwjgl.opengl.DisplayMode;
import org.lwjgl.opengl.GL11;

public class LWJGLTest {
public static void main(String[] args) {
Thread gameThread = new Thread(new Runnable() {
void setMVP(final Matrix4f matrix, ByteBuffer byteBuffer) {
FloatBuffer buf = byteBuffer.asFloatBuffer();
int idx = 0;
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 4; j++) {
buf.put(idx, matrix.m[i][j]);
idx++;
}
}
buf.position(0);
GL11.glLoadMatrix(buf);
}

@Override
public void run() {
try {
Display.setDisplayMode(new DisplayMode(800, 600));
Display.create();
} catch (LWJGLException e) {
e.printStackTrace();
return;
}

GL11.glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
GL11.glDisable(GL11.GL_CULL_FACE);

ByteBuffer tempMatrixBuffer = ByteBuffer.allocateDirect(16 * (Float.SIZE / 8));

while (!Display.isCloseRequested()) {
Display.sync(60);

// Set viewport
GL11.glViewport(0, 0, Display.getWidth(), Display.getHeight());

// Clear frame
GL11.glClear(GL11.GL_COLOR_BUFFER_BIT | GL11.GL_DEPTH_BUFFER_BIT);

// Calculate ortho projection and load it into opengl
Matrix4f mvp = Matrix4f.createOrtho(0.0f, (float)Display.getWidth(), (float)Display.getHeight(), 0.0f, -1.0f, 1.0f);
mvp = Matrix4f.mul(mvp, Matrix4f.createTranslation(0.0f, 0.0f, 0.0f));
setMVP(mvp, tempMatrixBuffer);

// Draw a red quad from pos 0x0 size 100x100
GL11.glColor3f(0.0f, 1.0f, 0.0f);
GL11.glBegin(GL11.GL_QUADS);
GL11.glVertex2i(0, 0);
GL11.glVertex2i(100, 0);
GL11.glVertex2i(100, 100);
GL11.glVertex2i(0, 100);
GL11.glEnd();

// Swap buffers
Display.update();
}

Display.destroy();
}
});
gameThread.start();
}

}


There will be now exception thrown, but it simply does not work... the quad is not seen.
I also checked the matrix values and it was exactly the same as my native c++ application.
Therefore is nothing wrong with my matrix implementation.
Of course i checked the FloatBuffer values and the values seems to be uploaded fine...

What do i am wrong?

Regards,
Final

Make sure you are setting the byte order correctly on the ByteBuffer. Try calling this instead: ByteBuffer.allocateDirect(16 * (Float.SIZE / 8)).order(ByteOrder.nativeOrder())

Quote from: Fool Running on May 22, 2012, 12:34:25
Make sure you are setting the byte order correctly on the ByteBuffer. Try calling this instead:

Code Select Expand

ByteBuffer.allocateDirect(16 * (Float.SIZE / 8)).order(ByteOrder.nativeOrder())

Damn, i knew it... it has something to do with this. Java uses big endian by default...
But anyway, Thanks... it works now.