frustrum culling (camera inside shadow volume) ?

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bytecode77 (Posted 2006) [#1]

hello! in order to optimize our shadow system to about 1.5x speed i have to do it as follows: the object is a shpere which represents the bounding sphere of an entity (or box or what ever the algorithm supports)... i need to know whether the camera is inside the red area below the shadow caster. thank you :)

b32 (Posted 2006) [#2]

I'm not sure if this works, I don't know how to test it. ;------------------------------------------------------------------------------------------------------- ; TestForArea() ;------------------------------------------------------------------------------------------------------- ;combine IsInRedArea and IsBelowCaster Function TestForArea(camera, light, entity, radius) test1 = IsInRedArea(camera, light, entity, radius) test2 = IsBelowCaster(camera, light, entity, radius) Return (test1 And test2) End Function ;------------------------------------------------------------------------------------------------------- ; IsInRedArea() ;------------------------------------------------------------------------------------------------------- ;if camera is within red area Function IsInRedArea(camera, light, entity, radius ) ;distance light-entity dist1# = EntityDistance(light, entity) ;distance light-camera dist2# = EntityDistance(light, camera) ;light x,y,z x1# = EntityX(light) y1# = EntityY(light) z1# = EntityZ(light) ;entity x,y,z x2# = EntityX(entity) y2# = EntityY(entity) z2# = EntityZ(entity) ;extrapolate entity position to the same distance as the distance from camera to light x# = ((x2 - x1) * dist2 / dist1) + x1 y# = ((y2 - y1) * dist2 / dist1) + y1 z# = ((z2 - z1) * dist2 / dist1) + z1 ;position a pivot at that location temppivot = CreatePivot() PositionEntity temppivot, x, y, z ;distance camera-new location dist# = EntityDistance(camera, temppivot) FreeEntity temppivot ;check if this distance is within the radius Return (dist < radius) End Function ;------------------------------------------------------------------------------------------------------- ; IsBelowCaster() ;------------------------------------------------------------------------------------------------------- ;if camera is outside entity radius and farther away from the light than the entity Function IsBelowCaster(camera, light, entity, radius) ;if the camera is closer to the light than the entity, return 0 If EntityDistance(camera, light) < EntityDistance(camera, entity) Then Return 0 ;return if the distance camera-entity is outside the radius Return (EntityDistance(camera, entity) > radius) End Function

bytecode77 (Posted 2006) [#3]

hey bram thx it works seamless! thank you. you helped me alot. i will release an update as soon as i finished this. cya!!

bytecode77 (Posted 2006) [#4]

one issue: this code is made for parrallel light, right? what if my lightsource is a pointlight? then it is making strange thigs...

b32 (Posted 2006) [#5]

Yes, you are right, sorry. I forgot to include scale the radius# in IsInRedArea(). This might be better: ;------------------------------------------------------------------------------------------------------- ; TestForArea() ;------------------------------------------------------------------------------------------------------- ;combine IsInRedArea and IsBelowCaster Function TestForArea(camera, light, entity, radius#) test1 = IsInRedArea(camera, light, entity, radius) test2 = IsBelowCaster(camera, light, entity, radius) Return (test1 And test2) End Function ;------------------------------------------------------------------------------------------------------- ; IsInRedArea() ;------------------------------------------------------------------------------------------------------- ;if camera is within red area Function IsInRedArea(camera, light, entity, radius#) ;distance light-entity dist1# = EntityDistance(light, entity) ;distance light-camera dist2# = EntityDistance(light, camera) ;light x,y,z x1# = EntityX(light) y1# = EntityY(light) z1# = EntityZ(light) r1# = 0 ;entity x,y,z x2# = EntityX(entity) y2# = EntityY(entity) z2# = EntityZ(entity) r2# = radius ;extrapolate entity position to the same distance as the distance from camera to light x# = ((x2 - x1) * dist2 / dist1) + x1 y# = ((y2 - y1) * dist2 / dist1) + y1 z# = ((z2 - z1) * dist2 / dist1) + z1 r# = ((r2 - r1) * dist2 / dist1) + r1 ;position a pivot at that location temppivot = CreatePivot() PositionEntity temppivot, x, y, z ;distance camera-new location dist# = EntityDistance(camera, temppivot) FreeEntity temppivot ;check if this distance is within the radius Return (dist < r#) End Function ;------------------------------------------------------------------------------------------------------- ; IsBelowCaster() ;------------------------------------------------------------------------------------------------------- ;if camera is outside entity radius and farther away from the light than the entity Function IsBelowCaster(camera, light, entity, radius#) ;if the camera is closer to the light than the entity, return 0 If EntityDistance(camera, light) < EntityDistance(camera, entity) Then Return 0 ;return if the distance camera-entity is outside the radius Return (EntityDistance(camera, entity) > radius) End Function Note that instead of using EntityDistance() you could also calculate the distance between two points yourself. It will save creating/destroying a pivot for each calculation.

bytecode77 (Posted 2006) [#6]

thank you :)

b32 (Posted 2006) [#7]

no problem, Teufel!