Drawing the scene Shadow mapping

final scene, rendered ambient shadows.

drawing scene shadows can done in several different ways. if programmable shaders available, depth map test may performed fragment shader draws object in shadow or lighted depending on result, drawing scene in single pass (after initial earlier pass generate shadow map).

if shaders not available, performing depth map test must implemented hardware extension (such gl_arb_shadow), not allow choice between 2 lighting models (lit , shadowed), , necessitate more rendering passes:

the example pictures in article used opengl extension gl_arb_shadow_ambient accomplish shadow map process in 2 passes.