To the more experienced users of this forum – how difficult it is/would it be to achieve these effects with accumulation buffers or otherwise? (For the record: I don’t know anything about accumulation buffers)
Is it something which might be out of a newbie’s reach/too much effort?
I haven’t had any luck finding any online information about these effects with LWJGL. Has anyone created anything which adopts these effects? Any insight and honest discouragement greatly appreciated! 
Cheers,
Rob
found something for ya here:
though it uses glut, the general technique should work fine
For a simple and quite nice motion blur, I’d go with a following class, for instance (requires GL_TEXTURE_RECTANGLE_EXT):
public class MotionBlurPostFilter
{
private int textureHandle;
private int width;
private int height;
private float alpha;
private float zoom;
private int frameCount;
public MotionBlurPostFilter(int width, int height, float alpha, float zoom, GL gl)
{
this.width = width;
this.height = height;
this.alpha = alpha;
this.zoom = zoom;
setupTexture(gl);
}
public void apply(GL gl)
{
gl.glEnable(GL.GL_TEXTURE_RECTANGLE_EXT);
gl.glBindTexture(GL.GL_TEXTURE_RECTANGLE_EXT, textureHandle);
if (frameCount++ > 0)
{
gl.glDisable(GL.GL_LIGHTING);
gl.glDisable(GL.GL_DEPTH_TEST);
gl.glEnable(GL.GL_BLEND);
gl.glBlendFunc(GL.GL_SRC_ALPHA, GL.GL_ONE_MINUS_SRC_ALPHA);
gl.glTexEnvi(GL.GL_TEXTURE_ENV, GL.GL_TEXTURE_ENV_MODE, GL.GL_REPLACE);
gl.glColor4f(0, 0, 0, alpha);
viewOrtho(gl);
gl.glBegin(GL.GL_QUADS);
{
gl.glTexCoord2f(width, 0);
gl.glVertex2f(-zoom, -zoom);
gl.glTexCoord2f(width, height);
gl.glVertex2f(-zoom, 1.0f + zoom);
gl.glTexCoord2f(0, height);
gl.glVertex2f(1.0f + zoom, 1.0f + zoom);
gl.glTexCoord2f(0, 0);
gl.glVertex2f(1.0f + zoom, -zoom);
}
gl.glEnd();
viewPerspective(gl);
gl.glEnable(GL.GL_DEPTH_TEST);
}
gl.glCopyTexSubImage2D(GL.GL_TEXTURE_RECTANGLE_EXT, 0, 0, 0, 0, 0, width, height);
gl.glDisable(GL.GL_TEXTURE_RECTANGLE_EXT);
}
private void setupTexture(GL gl)
{
int[] textureHandles = new int[1];
gl.glGenTextures(1, textureHandles);
textureHandle = textureHandles[0];
int textureData[] = new int[width * height * 3];
gl.glEnable(GL.GL_TEXTURE_RECTANGLE_EXT);
gl.glBindTexture(GL.GL_TEXTURE_RECTANGLE_EXT, textureHandle);
gl.glTexImage2D(GL.GL_TEXTURE_RECTANGLE_EXT, 0, 3, width, height, 0, GL.GL_RGB, GL.GL_UNSIGNED_INT, textureData);
gl.glTexParameteri(GL.GL_TEXTURE_RECTANGLE_EXT, GL.GL_TEXTURE_MIN_FILTER, GL.GL_LINEAR);
gl.glTexParameteri(GL.GL_TEXTURE_RECTANGLE_EXT, GL.GL_TEXTURE_MAG_FILTER, GL.GL_LINEAR);
gl.glDisable(GL.GL_TEXTURE_RECTANGLE_EXT);
}
void viewOrtho(GL gl)
{
gl.glMatrixMode(GL.GL_PROJECTION);
gl.glPushMatrix();
gl.glLoadIdentity();
gl.glOrtho(1, 0, 0, 1, -1, 1000000);
gl.glMatrixMode(GL.GL_MODELVIEW);
gl.glPushMatrix();
gl.glLoadIdentity();
}
void viewPerspective(GL gl)
{
gl.glMatrixMode(GL.GL_PROJECTION);
gl.glPopMatrix();
gl.glMatrixMode(GL.GL_MODELVIEW);
gl.glPopMatrix();
}
}
Usage example:
// Creation
mb = new MotionBlurPostFilter(screen.getWidth(), screen.getHeight(), 0.7f, 0, gl);
// While in rendering loop:
while(!exited)
{
// Render scene
scene.render();
// Apply motion blur
mb.apply(gl);
}
…And yeah, I know it’s not optimized or anything. This was originally written for JOGL, thus the GL instance :). Hope you got something out of this fuzzy (written in less than a minute ;)) description.
Cheers
HI,
this can be done when rendering into a texture. The Nehe Tutorial
Nr: 36 shows a Radial Blur. I ported this to lwjgl (0.7) you
can found it there Nehe 36. If you like i can send you the source.
Stay Tuned,
jens
That’s true. However, the NeHe lesson #36 does not actually render to the texture, but copies the viewport contents to it. This is what my code does too - plus it uses a non-power-of-2 texture, which gives a better matching resolution for the blurred texture.
Yep, right i forgotten this.
I saw somewhere that also pbuffers can be used - but pbuffers are not
well supported yet. This will bring up some more fps.
-jens