Depth buffer to 3d coordinates?

I'm having trouble transforming screen coordinates back to 3d, which this post describes- can anyone help me?





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Update - I've got it figured out now, I should have been using gluUnProject:



FloatBuffer fb;

fb = BufferUtil.newFloatBuffer(width*height);

gl.glReadPixels(0, 0, width, height, GL.GL_DEPTH_COMPONENT, GL.GL_FLOAT, fb);
fb.rewind();

int viewport[] = new int[4];
double[] proj=new double[16];
double[] model=new double[16];
gl.glGetIntegerv(GL.GL_VIEWPORT, viewport, 0);
gl.glGetDoublev(GL.GL_PROJECTION_MATRIX,proj,0);
gl.glGetDoublev(GL.GL_MODELVIEW_MATRIX,model,0);

...
for(int i...
for (int j...
...
glu.gluUnProject(i,height-j,rawd, model,0,proj,0,viewport,0,pos,0);
float d = (float)-pos[2];


After all that depth d will be linear and in proper world coordinates.