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ajmas

Status panes in front of scene?

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I am wanting to create a scene and at the same time draw some panes in front of the scene which would allow the user to change certain settings. In doing so I want to ensure that any manipulattion of my scene does not interfere with my panes. Can anyone suggest how to do this or point me towards some examples?

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Thanks for the reply and for the link.

In reality I am more interested in learning the mechanics of doing it myself for the moment. I am still learning OpenGL and feel that I would rather understand how this is done in OpenGL, before using a ready built solution.

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The basics of a 2D overlay/HUD are to render your 3D scene with a perspective projection and then switch to an orthographic projection (with glOrtho) to render your status panel. There's also a nice entry in the forum FAQ about 2D with OpenGL.

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I actually just worked this out myself. Here is some psuedocode of what I did:

pushPerspectiveProjection();

while(running)
pushOrthographicProjection();
drawUI();
popProjection();

drawScene();
end

pushOrthographicProjection()
glPushAttrib(GL_TRANSFORM_BIT);
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
glOrtho(0.0f, width, 0.0f, height, -1.0f, 1.0f);
glPopAttrib();
end

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Thanks, this work beautifully. Some actual code, in Java using JOGL, for anyone else who happens to come along this thread:


void pushOrthographicProjection( GL gl ) {
gl.glPushAttrib(GL.GL_TRANSFORM_BIT);
gl.glMatrixMode(GL.GL_PROJECTION);
gl.glPushMatrix();
gl.glLoadIdentity();
gl.glOrtho(0.0f, getWidth(), 0.0f, getHeight(), -1.0f, 1.0f);
}

void popOrthographicProjection( GL gl ) {
gl.glPopMatrix();
gl.glPopAttrib();
}

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Just make sure you don't forget to toggle the matrix mode back before drawing ;)
Quote:
Original post by ajmas

void pushOrthographicProjection( GL gl ) {
gl.glPushAttrib(GL.GL_TRANSFORM_BIT);
gl.glMatrixMode(GL.GL_PROJECTION);
gl.glPushMatrix();
gl.glLoadIdentity();
gl.glOrtho(0.0f, getWidth(), 0.0f, getHeight(), -1.0f, 1.0f);
gl.glMatrixMode(GL.GL_MODELVIEW);
}

void popOrthographicProjection( GL gl ) {
gl.glMatrixMode(GL.GL_PROJECTION);
gl.glPopMatrix();
gl.glMatrixMode(GL.GL_MODELVIEW);
gl.glPopAttrib();
}

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