Depth map test Shadow mapping

depth map test failures.

once light-space coordinates found, x , y values correspond location in depth map texture, , z value corresponds associated depth, can tested against depth map.

if z value greater value stored in depth map @ appropriate (x,y) location, object considered behind occluding object, , should marked failure, drawn in shadow drawing process. otherwise should drawn lit.

if (x,y) location falls outside depth map, programmer must either decide surface should lit or shadowed default (usually lit).

in shader implementation, test done @ fragment level. also, care needs taken when selecting type of texture map storage used hardware: if interpolation cannot done, shadow appear have sharp jagged edge (an effect can reduced greater shadow map resolution).

it possible modify depth map test produce shadows soft edge using range of values (based on proximity edge of shadow) rather pass or fail.

the shadow mapping technique can modified draw texture onto lit regions, simulating effect of projector. picture above, captioned visualization of depth map projected onto scene example of such process.