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70 lines
2.6 KiB
70 lines
2.6 KiB
/*
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* This file is part of MXE. See LICENSE.md for licensing information.
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*/
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// taken from: doc/examples/Hello Chipmunk.html
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#include <stdio.h>
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#include <chipmunk/chipmunk.h>
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int main(void){
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// cpVect is a 2D vector and cpv() is a shortcut for initializing them.
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cpVect gravity = cpv(0, -100);
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// Create an empty space.
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cpSpace *space = cpSpaceNew();
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cpSpaceSetGravity(space, gravity);
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// Add a static line segment shape for the ground.
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// We'll make it slightly tilted so the ball will roll off.
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// We attach it to a static body to tell Chipmunk it shouldn't be movable.
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cpShape *ground = cpSegmentShapeNew(cpSpaceGetStaticBody(space), cpv(-20, 5), cpv(20, -5), 0);
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cpShapeSetFriction(ground, 1);
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cpSpaceAddShape(space, ground);
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// Now let's make a ball that falls onto the line and rolls off.
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// First we need to make a cpBody to hold the physical properties of the object.
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// These include the mass, position, velocity, angle, etc. of the object.
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// Then we attach collision shapes to the cpBody to give it a size and shape.
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cpFloat radius = 5;
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cpFloat mass = 1;
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// The moment of inertia is like mass for rotation
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// Use the cpMomentFor*() functions to help you approximate it.
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cpFloat moment = cpMomentForCircle(mass, 0, radius, cpvzero);
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// The cpSpaceAdd*() functions return the thing that you are adding.
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// It's convenient to create and add an object in one line.
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cpBody *ballBody = cpSpaceAddBody(space, cpBodyNew(mass, moment));
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cpBodySetPosition(ballBody, cpv(0, 15));
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// Now we create the collision shape for the ball.
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// You can create multiple collision shapes that point to the same body.
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// They will all be attached to the body and move around to follow it.
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cpShape *ballShape = cpSpaceAddShape(space, cpCircleShapeNew(ballBody, radius, cpvzero));
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cpShapeSetFriction(ballShape, 0.7);
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// Now that it's all set up, we simulate all the objects in the space by
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// stepping forward through time in small increments called steps.
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// It is *highly* recommended to use a fixed size time step.
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cpFloat timeStep = 1.0/60.0;
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for(cpFloat time = 0; time < 2; time += timeStep){
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cpVect pos = cpBodyGetPosition(ballBody);
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cpVect vel = cpBodyGetVelocity(ballBody);
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printf(
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"Time is %5.2f. ballBody is at (%5.2f, %5.2f). It's velocity is (%5.2f, %5.2f)\n",
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time, pos.x, pos.y, vel.x, vel.y
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);
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cpSpaceStep(space, timeStep);
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}
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// Clean up our objects and exit!
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cpShapeFree(ballShape);
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cpBodyFree(ballBody);
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cpShapeFree(ground);
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cpSpaceFree(space);
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return 0;
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}
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