[bb] Rigid Body Simulation by Sweenie [ 1+ years ago ]

[BlitzBot]

Title : Rigid Body Simulation
Author : Sweenie
Posted : 1+ years ago

Description : This is the beginning of a simple Rigid Body simulation in Blitz.
No collisions so far.(So the difficult part is yet to be done)

Code :

Code: BlitzBasic

1. Graphics3D 800,600,0,2
2. SetBuffer BackBuffer()
3.  
4. camera = CreateCamera()
5. PositionEntity camera,0,0,-10
6.  
7. WireFrame True
8.  
9. Global Cprod_x#
10. Global Cprod_y#
11. Global Cprod_z#
12. Const NEARZERO# = 0.0001
13.  
14. ;RigidBody Type
15.  
16. Type RigidBody
17.  
18.  Field Mass#
19.  
20.  Field Com_x# ; Center Of Mass
21.  Field Com_y#
22.  Field Com_z#
23.  Field Linearvel_x# ; Linear Velocity
24.  Field Linearvel_y#
25.  Field Linearvel_z#
26.  Field Linearacc_x# ; Linear Acceleration
27.  Field Linearacc_y#
28.  Field Linearacc_z#
29.  Field Forcevec_x# ; Force Vector
30.  Field Forcevec_y#
31.  Field Forcevec_z#
32.  Field Forceloc_x# ; Force Location
33.  Field Forceloc_y#
34.  Field Forceloc_z#
35.  
36.  Field Rotangle_x# ; Rotation Angle (Orientation)
37.  Field Rotangle_y#
38.  Field Rotangle_z#
39.  Field Angularvel_x# ; Angular Velocity
40.  Field Angularvel_y#
41.  Field Angularvel_z#
42.  Field Angularacc_x# ; Angular Acceleration
43.  Field Angularacc_y#
44.  Field Angularacc_z#
45.  Field Inertia_x# ; Rotational Inertia
46.  Field Inertia_y#
47.  Field Inertia_z#
48.  Field Torque_x# ; eh... Just Torque ;)
49.  Field Torque_y#
50.  Field Torque_z#
51.  
52.  Field Coeff# ; Coefficient of restitution / "Bounce Factor" 0.0 = Not elastic, 1.0 = VERY elastic, 1.1 = Too Elastic ;)
53.  Field Friction# ; * Not implemented yet *
54.  Field LinearDamping#
55.  Field AngularDamping#
56.  
57. End Type
58.  
59.  
60. RB.RigidBody = New RigidBody
61. RBMass#=1.0
62. RBInertia_x#=0.4
63. RBInertia_y#=0.4
64. RBInertia_z#=0.4
65. RBLinearDamping# = 0.001
66. RBAngularDamping# = 0.01
67.  
68. RB_Mesh = CreateSphere()
69.  
70. While Not KeyHit(1)
71.  
72. UpdateBody RB,0.02
73.  
74. PositionEntity RB_Mesh,RBCom_x#,RBCom_y#,RBCom_z#
75. RotateEntity RB_Mesh,RBRotangle_x#,-RBRotangle_y#,RBRotangle_z#
76.  
77. If KeyDown(205) Then ; Right
78.  RBForcevec_x# = 1.0
79.  RBForcevec_y# = 0.0
80.  RBForcevec_z# = 0.0
81.  RBForceloc_x# = 0.0
82.  RBForceloc_y# = 25.0
83.  RBForceloc_z# = -25.0
84. ElseIf KeyDown(203) Then ; Left
85.  RBForcevec_x# = -2.0
86.  RBForcevec_y# = 0.0
87.  RBForcevec_z# = 0.0
88.  RBForceloc_x# = 0.0
89.  RBForceloc_y# = 15.0
90.  RBForceloc_z# = -5.0
91. Else
92.  RBForcevec_x# = 0.0
93.  RBForcevec_y# = 0.0
94.  RBForcevec_z# = 0.0
95. EndIf
96.  
97.  
98. RenderWorld
99.  
100. Flip
101.  
102. Wend
103. End
104.  
105.  
106. Function UpdateBody(Body.RigidBody,dt#)
107.  
108.  ; *** Linear Dynamics ***
109.  
110.  ;Linear Acceleration
111.  If BodyMass#>0 Then
112.   BodyLinearacc_x# = BodyForcevec_x# / BodyMass#
113.   BodyLinearacc_y# = BodyForcevec_y# / BodyMass#
114.   BodyLinearacc_z# = BodyForcevec_z# / BodyMass#
115.  EndIf
116.  
117.  ;Linear Velocity
118.  BodyLinearvel_x# = BodyLinearvel_x# + BodyLinearacc_x# * dt#
119.  BodyLinearvel_y# = BodyLinearvel_y# + BodyLinearacc_y# * dt#
120.  BodyLinearvel_z# = BodyLinearvel_z# + BodyLinearacc_z# * dt#
121.  
122.  ;Center Of Mass
123.  BodyCom_x# = BodyCom_x# + BodyLinearvel_x# * dt#
124.  BodyCom_y# = BodyCom_y# + BodyLinearvel_y# * dt#
125.  BodyCom_z# = BodyCom_z# + BodyLinearvel_z# * dt#
126.  
127.  
128.  ; *** Rotational Dynamics ***
129.  
130.  ;Torque
131.  CrossProduct BodyForceloc_x#,BodyForceloc_y#,BodyForceloc_z#,BodyForcevec_x#,BodyForcevec_y#,BodyForcevec_z#
132.  BodyTorque_x#=Cprod_x#
133.  BodyTorque_y#=Cprod_y#
134.  BodyTorque_z#=Cprod_z#
135.  
136.  ;Angular Acceleration
137.  BodyAngularacc_x# = BodyTorque_x# / BodyInertia_x#
138.  BodyAngularacc_y# = BodyTorque_y# / BodyInertia_y#
139.  BodyAngularacc_z# = BodyTorque_z# / BodyInertia_z#
140.  
141.  ;Angular Velocity
142.  BodyAngularvel_x# = BodyAngularvel_x# + BodyAngularacc_x# * dt#
143.  BodyAngularvel_y# = BodyAngularvel_y# + BodyAngularacc_y# * dt#
144.  BodyAngularvel_z# = BodyAngularvel_z# + BodyAngularacc_z# * dt#
145.  
146.  ;Angles of rotation / Orientation
147.  BodyRotangle_x# = BodyRotangle_x# + BodyAngularvel_x# * dt#
148.  BodyRotangle_y# = BodyRotangle_y# + BodyAngularvel_y# * dt#
149.  BodyRotangle_z# = BodyRotangle_z# + BodyAngularvel_z# * dt#
150.  
151.  ;Damp Linear & Angular Velocity
152.  BodyLinearvel_x#=BodyLinearvel_x#*(1.0-BodyLinearDamping#)
153.  BodyLinearvel_y#=BodyLinearvel_y#*(1.0-BodyLinearDamping#)
154.  BodyLinearvel_z#=BodyLinearvel_z#*(1.0-BodyLinearDamping#)
155.  BodyAngularvel_x#=BodyAngularvel_x#*(1.0-BodyAngularDamping#)
156.  BodyAngularvel_y#=BodyAngularvel_y#*(1.0-BodyAngularDamping#)
157.  BodyAngularvel_z#=BodyAngularvel_z#*(1.0-BodyAngularDamping#)
158.  
159.  ;Reset Velocities If Near Zero Value / *Hack* ;) Not necessary but prevents jittering when Body is considered not moving.
160.  If Abs(BodyLinearvel_x#)<NEARZERO# Then BodyLinearvel_x#=0.0
161.  If Abs(BodyLinearvel_y#)<NEARZERO# Then BodyLinearvel_y#=0.0
162.  If Abs(BodyLinearvel_z#)<NEARZERO# Then BodyLinearvel_z#=0.0
163.  If Abs(BodyAngularvel_x#)<NEARZERO# Then BodyAngularvel_x#=0.0
164.  If Abs(BodyAngularvel_y#)<NEARZERO# Then BodyAngularvel_y#=0.0
165.  If Abs(BodyAngularvel_z#)<NEARZERO# Then BodyAngularvel_z#=0.0
166.  
167.  
168. End Function
169.  
170. Function DotProduct#(x1#,y1#,z1#,x2#,y2#,z2#)
171.         Return (x1#*x2#)+(y1#*y2#)+(z1#*z2#)
172. End Function
173.  
174. Function CrossProduct(x1#,y1#,z1#,x2#,y2#,z2#)
175.         Cprod_x#=(y1#*z2#)-(z1#*y2#)
176.         Cprod_y#=(z1#*x2#)-(x1#*z2#)
177.         Cprod_z#=(x1#*y2#)-(y1#*x2#)
178. End Function

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