The back buffer is initialised to the background pixel value. BrPixelmapFill(back_buffer,0)
fills the back buffer with 0's, setting the background pixel colour to black.
The Z-Buffer is then initialised to the largest representable z-value. This is 0xFFFF for a 16-bit buffer. 0xFFFFFFFF is passed to accommodate Z-Buffer depths up to 32 bits.
for(i=0; i < 360; i++) { BrPixelmapFill(back_buffer,0); BrPixelmapFill(depth_buffer,0xFFFFFFFF); BrZbSceneRender(world,observer,back_buffer,depth_buffer); BrPixelmapDoubleBuffer(screen_buffer,back_buffer); BrMatrix34PostRotateX(&cube->t.t.mat,BR_ANGLE_DEG(2.0)); }
BrZbSceneRender
renders the scene into back_buffer
. BrPixelmapDoubleBuffer
then `swaps' screen_buffer
and back_buffer
(see section on `Double Buffering' in Chapter 1) so the newly rendered image is displayed.For each iteration of the loop, cube is rotated 2xb0 about the x-axis.