CollisionNY# ( entity,collision_index )
Parameters
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entity - entity handle collision_index - index of the collision, from 1 to CountCollisions( entity ) |
Description
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Returns the y component of the normal of one of an entity's collisions. The normal is a unit-length vector pointing directly away from the surface the entity hit in collision number collision_index of the last UpdateWorld. The y component is the classic ground test: a value near 1 means the entity touched a level floor, near 0 a vertical wall - so one compare tells a platformer whether the player may jump again. In debug mode an index outside 1...CountCollisions( entity ) is a runtime error. See also: CollisionNX, CollisionNZ, CollisionY, CountCollisions, AlignToVector. |
Example
; CollisionNY 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 ; The floor is scenery too in this example, so resting on it is a collision floor=CreatePlane() EntityColor floor,70,110,70 EntityType floor,type_scenery ; The player ball is the collision SOURCE, so it needs an ellipsoid radius player=CreateSphere() EntityColor player,220,60,60 PositionEntity player,0,4,0 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 ; Gravity - the ball drops onto the floor and stays pressed against it MoveEntity player,0,-0.05,0 ; 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" ; CollisionNY is the y part of the collision normal - it points back at the ball n=CountCollisions(player) If n=0 Then Text 0,20,"CollisionNY: no collisions this frame" For i=1 To n Text 0,20*i,"CollisionNY(player,"+i+") = "+CollisionNY(player,i) Next Text 0,80,"The floor pushes straight up: NY = 1. Wall contacts are level: NY = 0" Flip Wend End
Index