1 /* Copyright (c) 2007 Scott Lembcke
2 *
3 * Permission is hereby granted, free of charge, to any person obtaining a copy
4 * of this software and associated documentation files (the "Software"), to deal
5 * in the Software without restriction, including without limitation the rights
6 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
7 * copies of the Software, and to permit persons to whom the Software is
8 * furnished to do so, subject to the following conditions:
9 *
10 * The above copyright notice and this permission notice shall be included in
11 * all copies or substantial portions of the Software.
12 *
13 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
14 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
15 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
16 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
17 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
18 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
19 * SOFTWARE.
20 */
21
22 #include "chipmunk/chipmunk.h"
23 #include "ChipmunkDemo.h"
24
25 static cpBody *tankBody, *tankControlBody;
26
27 static void
update(cpSpace * space,double dt)28 update(cpSpace *space, double dt)
29 {
30 // turn the control body based on the angle relative to the actual body
31 cpVect mouseDelta = cpvsub(ChipmunkDemoMouse, cpBodyGetPosition(tankBody));
32 cpFloat turn = cpvtoangle(cpvunrotate(cpBodyGetRotation(tankBody), mouseDelta));
33 cpBodySetAngle(tankControlBody, cpBodyGetAngle(tankBody) - turn);
34
35 // drive the tank towards the mouse
36 if(cpvnear(ChipmunkDemoMouse, cpBodyGetPosition(tankBody), 30.0)){
37 cpBodySetVelocity(tankControlBody, cpvzero); // stop
38 } else {
39 cpFloat direction = (cpvdot(mouseDelta, cpBodyGetRotation(tankBody)) > 0.0 ? 1.0 : -1.0);
40 cpBodySetVelocity(tankControlBody, cpvrotate(cpBodyGetRotation(tankBody), cpv(30.0f*direction, 0.0f)));
41 }
42
43 cpSpaceStep(space, dt);
44 }
45
46 static cpBody *
add_box(cpSpace * space,cpFloat size,cpFloat mass)47 add_box(cpSpace *space, cpFloat size, cpFloat mass)
48 {
49 cpFloat radius = cpvlength(cpv(size, size));
50
51 cpBody *body = cpSpaceAddBody(space, cpBodyNew(mass, cpMomentForBox(mass, size, size)));
52 cpBodySetPosition(body, cpv(frand()*(640 - 2*radius) - (320 - radius), frand()*(480 - 2*radius) - (240 - radius)));
53
54 cpShape *shape = cpSpaceAddShape(space, cpBoxShapeNew(body, size, size, 0.0));
55 cpShapeSetElasticity(shape, 0.0f);
56 cpShapeSetFriction(shape, 0.7f);
57
58 return body;
59 }
60
61 static cpSpace *
init(void)62 init(void)
63 {
64 ChipmunkDemoMessageString = "Use the mouse to drive the tank, it will follow the cursor.";
65
66 cpSpace *space = cpSpaceNew();
67 cpSpaceSetIterations(space, 10);
68 cpSpaceSetSleepTimeThreshold(space, 0.5f);
69
70 cpBody *staticBody = cpSpaceGetStaticBody(space);
71 cpShape *shape;
72
73 // Create segments around the edge of the screen.
74 shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(-320,-240), cpv(-320,240), 0.0f));
75 cpShapeSetElasticity(shape, 1.0f);
76 cpShapeSetFriction(shape, 1.0f);
77 cpShapeSetFilter(shape, NOT_GRABBABLE_FILTER);
78
79 shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(320,-240), cpv(320,240), 0.0f));
80 cpShapeSetElasticity(shape, 1.0f);
81 cpShapeSetFriction(shape, 1.0f);
82 cpShapeSetFilter(shape, NOT_GRABBABLE_FILTER);
83
84 shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(-320,-240), cpv(320,-240), 0.0f));
85 cpShapeSetElasticity(shape, 1.0f);
86 cpShapeSetFriction(shape, 1.0f);
87 cpShapeSetFilter(shape, NOT_GRABBABLE_FILTER);
88
89 shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(-320,240), cpv(320,240), 0.0f));
90 cpShapeSetElasticity(shape, 1.0f);
91 cpShapeSetFriction(shape, 1.0f);
92 cpShapeSetFilter(shape, NOT_GRABBABLE_FILTER);
93
94 for(int i=0; i<50; i++){
95 cpBody *body = add_box(space, 20, 1);
96
97 cpConstraint *pivot = cpSpaceAddConstraint(space, cpPivotJointNew2(staticBody, body, cpvzero, cpvzero));
98 cpConstraintSetMaxBias(pivot, 0); // disable joint correction
99 cpConstraintSetMaxForce(pivot, 1000.0f); // emulate linear friction
100
101 cpConstraint *gear = cpSpaceAddConstraint(space, cpGearJointNew(staticBody, body, 0.0f, 1.0f));
102 cpConstraintSetMaxBias(gear, 0); // disable joint correction
103 cpConstraintSetMaxForce(gear, 5000.0f); // emulate angular friction
104 }
105
106 // We joint the tank to the control body and control the tank indirectly by modifying the control body.
107 tankControlBody = cpSpaceAddBody(space, cpBodyNewKinematic());
108 tankBody = add_box(space, 30, 10);
109
110 cpConstraint *pivot = cpSpaceAddConstraint(space, cpPivotJointNew2(tankControlBody, tankBody, cpvzero, cpvzero));
111 cpConstraintSetMaxBias(pivot, 0); // disable joint correction
112 cpConstraintSetMaxForce(pivot, 10000.0f); // emulate linear friction
113
114 cpConstraint *gear = cpSpaceAddConstraint(space, cpGearJointNew(tankControlBody, tankBody, 0.0f, 1.0f));
115 cpConstraintSetErrorBias(gear, 0); // attempt to fully correct the joint each step
116 cpConstraintSetMaxBias(gear, 1.2f); // but limit it's angular correction rate
117 cpConstraintSetMaxForce(gear, 50000.0f); // emulate angular friction
118
119 return space;
120 }
121
122 static void
destroy(cpSpace * space)123 destroy(cpSpace *space)
124 {
125 ChipmunkDemoFreeSpaceChildren(space);
126 cpSpaceFree(space);
127 }
128
129 ChipmunkDemo Tank = {
130 "Tank",
131 1.0/60.0,
132 init,
133 update,
134 ChipmunkDemoDefaultDrawImpl,
135 destroy,
136 };
137