[bb] Using LinePick to do sphere-to-sphere collisions by Ken Lynch [ 1+ years ago ]

[BlitzBot]

Title : Using LinePick to do sphere-to-sphere collisions
Author : Ken Lynch
Posted : 1+ years ago

Description : A visual example of how the LinePick command works and how you could use it to do sphere-to-sphere collisions with a bit more control than using Blitz's collision system.

Hope someone finds it useful.

Code :

Code: BlitzBasic

1. ;
2. ; LinePick sphere-to-sphere collision
3. ;
4.  
5. Graphics3D 800, 600
6.  
7. light = CreateLight()
8.  
9. pivot = CreatePivot()
10.  
11. camera = CreateCamera(pivot)
12. PositionEntity camera, 0, 10, 0
13. RotateEntity camera, 90, 0, 0
14.  
15. ;
16. ; Player
17. ;
18. player = CreateSphere()
19. player_speed# = 0.1
20. PositionEntity player, 0, 0, 5
21. EntityPickMode player, 1
22.  
23. ;
24. ; Sphere
25. ;
26. sphere = CreateSphere()
27. velocity# = 2
28. radius# = 1
29. sph = CreateCylinder()
30. EntityParent sph, sphere
31. ScaleEntity sph, 0.1, 1, 0.1
32. EntityColor sph, 255, 0, 0
33. PositionEntity sph, 0, 0, 1
34. AlignToVector sph, 0, 0, 1, 2
35.  
36. ;
37. ; Sphere to show where collision occurs
38. ;
39. collision = CreateSphere()
40. PositionEntity collision, 0, 0, 2
41. EntityColor collision, 0, 0, 255
42. EntityAlpha collision, 0.5
43. EntityFX collision, 1
44.  
45. ;
46. ; Cylinder to show normal vector
47. ;
48. normal = CreateCylinder()
49. ScaleEntity normal, 0.1, 1, 0.1
50. EntityColor normal, 255, 0, 0
51. HideEntity normal
52.  
53. Repeat
54.         ;
55.         ; Up key
56.         ;
57.         If KeyDown(200) Then MoveEntity player, 0, 0, player_speed
58.  
59.         ;
60.         ; Down key
61.         ;
62.         If KeyDown(208) Then MoveEntity player, 0, 0, -player_speed
63.  
64.         ;
65.         ; Left key
66.         ;
67.         If KeyDown(203) Then MoveEntity player, -player_speed, 0, 0
68.  
69.         ;
70.         ; Right key
71.         ;
72.         If KeyDown(205) Then MoveEntity player, player_speed, 0, 0
73.        
74.         ;
75.         ; Rotate sphere
76.         ;
77.         If KeyDown(44) Then TurnEntity sphere, 0, 1, 0
78.         If KeyDown(45) Then TurnEntity sphere, 0, -1, 0
79.        
80.         ;
81.         ; Increase/decrease velocity
82.         ;
83.         If KeyHit(12) Then velocity = velocity - 0.1
84.         If KeyHit(13) Then velocity = velocity + 0.1
85.        
86.         ;
87.         ; Increase/decrease radius
88.         ;
89.         If KeyHit(26) Then radius = radius - 0.1
90.         If KeyHit(27) Then radius = radius + 0.1
91.         ScaleEntity sphere, radius, radius, radius
92.        
93.         ;
94.         ; Transform velocity to global coordinates
95.         ;
96.         TFormVector 0, 0, velocity, sphere, 0
97.        
98.         ;
99.         ; Do the line pick
100.         ;
101.         If LinePick(0, 0, 0, TFormedX(), TFormedY(), TFormedZ(), radius) > 0 Then
102.                 ;
103.                 ; Show normal vector
104.                 ;
105.                 ShowEntity normal
106.                 ;
107.                 ; Move it to the picked position
108.                 ;
109.                 PositionEntity normal, PickedX(), PickedY(), PickedZ()
110.                 ;
111.                 ; Align it to the picked vector
112.                 ;
113.                 AlignToVector normal, PickedNX(), PickedNY(), PickedNZ(), 2
114.                 ;
115.                 ; Show collision sphere
116.                 ;
117.                 ShowEntity collision
118.                 ;
119.                 ; Move collision sphere
120.                 ;
121.                 PositionEntity collision, PickedX() + radius * PickedNX(), PickedY() + radius * PickedNY(), PickedZ() + radius * PickedNZ()
122.                 ;
123.                 ; Scale to radius
124.                 ;
125.                 ScaleEntity collision, radius, radius, radius
126.         Else
127.                 ;
128.                 ; Nothing was picked
129.                 ;
130.                 HideEntity normal
131.                 HideEntity collision
132.         End If
133.  
134.         RenderWorld
135.        
136.         Locate 0, 0
137.         Print "Velocity = "+velocity
138.         Print "Radius   = "+radius
139.         Print
140.         Print "Use cursor keys to move player"
141.         Print "Use z/x to rotate sphere left/right
142.         Print "Use -/= to decrease/increase velocity"
143.         Print "Use [/] to decrease/increase radius"
144.        
145.         Flip
146. Until KeyHit(1)

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