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entity - entity handle collision_index - index of the collision, from 1 to CountCollisions( entity ) |
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Returns the index of the triangle hit in one of an entity's collisions. The index refers to a triangle within the surface returned by CollisionSurface. Feed both to TriangleVertex and the vertex commands to inspect the exact polygon touched - the raw material for per-triangle effects like scorch marks or destructible panels. Triangle information exists only for ellipsoid-to-polygon collisions (method 2 of the Collisions command); ellipsoid and box collisions leave nothing meaningful here. In debug mode an index outside 1...CountCollisions( entity ) is a runtime error. See also: CollisionSurface, TriangleVertex, VertexX, CountCollisions, Collisions. |
; CollisionTriangle Example
; -------------------------
Graphics3D 640,480,0,2
SetBuffer BackBuffer()
; Collision type ids
type_player=1
type_scenery=2
; NOTE: fixed overhead camera - the arrow keys steer the PLAYER, not the camera
camera=CreateCamera()
PositionEntity camera,0,13,-13
RotateEntity camera,45,0,0
light=CreateLight()
RotateEntity light,60,30,0
floor=CreatePlane()
EntityColor floor,70,110,70
; The player ball is the collision SOURCE, so it needs an ellipsoid radius
player=CreateSphere()
EntityColor player,220,60,60
PositionEntity player,0,1,0
EntityRadius player,1
EntityType player,type_player
; Two walls meeting in a corner, plus a crate
wall1=CreateCube()
ScaleEntity wall1,7,1.5,0.5
PositionEntity wall1,0,1.5,7
EntityColor wall1,150,150,160
EntityType wall1,type_scenery
wall2=CreateCube()
ScaleEntity wall2,0.5,1.5,7
PositionEntity wall2,7,1.5,0
EntityColor wall2,150,150,160
EntityType wall2,type_scenery
crate=CreateCube()
ScaleEntity crate,1.2,1.2,1.2
PositionEntity crate,-4,1.2,3
EntityColor crate,200,160,60
EntityType crate,type_scenery
; Ellipsoid-to-polygon collisions with a sliding response
Collisions type_player,type_scenery,2,2
While Not KeyDown(1)
; Arrow keys steer the player ball
If KeyDown(200) Then MoveEntity player,0,0,0.1
If KeyDown(208) Then MoveEntity player,0,0,-0.1
If KeyDown(203) Then MoveEntity player,-0.1,0,0
If KeyDown(205) Then MoveEntity player,0.1,0,0
; UpdateWorld performs the collision checks and the slide response
UpdateWorld
RenderWorld
Text 0,0,"Arrow keys: drive the ball into the walls and crate Esc: exit"
; CollisionTriangle is the index of the triangle nearest the contact point
If CountCollisions(player)>0
Text 0,20,"CollisionTriangle(player,1) = "+CollisionTriangle(player,1)
Text 0,40,"Each cube face is two triangles - circle the crate and watch the index change"
Else
Text 0,20,"CollisionTriangle: no collisions this frame - push against something"
EndIf
Flip
Wend
End