add chipmunk physics package

1 files changed, 68 insertions, 0 deletions

diff --git a/src/chipmunk-test.c b/src/chipmunk-test.c
new file mode 100644
index 0000000..e425d34
--- /dev/null
+++ b/src/chipmunk-test.c
@@ -0,0 +1,68 @@
+/*
+ * This file is part of MXE.
+ * See index.html for further information.
+ */
+
+#include <stdio.h>
+#include <chipmunk/chipmunk.h>
+
+int main(void){
+    // cpVect is a 2D vector and cpv() is a shortcut for initializing them.
+    cpVect gravity = cpv(0, -100);
+
+    // Create an empty space.
+    cpSpace *space = cpSpaceNew();
+    cpSpaceSetGravity(space, gravity);
+
+    // Add a static line segment shape for the ground.
+    // We'll make it slightly tilted so the ball will roll off.
+    // We attach it to space->staticBody to tell Chipmunk it shouldn't be movable.
+    cpShape *ground = cpSegmentShapeNew(space->staticBody, cpv(-20, 5), cpv(20, -5), 0);
+    cpShapeSetFriction(ground, 1);
+    cpSpaceAddShape(space, ground);
+
+    // Now let's make a ball that falls onto the line and rolls off.
+    // First we need to make a cpBody to hold the physical properties of the object.
+    // These include the mass, position, velocity, angle, etc. of the object.
+    // Then we attach collision shapes to the cpBody to give it a size and shape.
+
+    cpFloat radius = 5;
+    cpFloat mass = 1;
+
+    // The moment of inertia is like mass for rotation
+    // Use the cpMomentFor*() functions to help you approximate it.
+    cpFloat moment = cpMomentForCircle(mass, 0, radius, cpvzero);
+
+    // The cpSpaceAdd*() functions return the thing that you are adding.
+    // It's convenient to create and add an object in one line.
+    cpBody *ballBody = cpSpaceAddBody(space, cpBodyNew(mass, moment));
+    cpBodySetPos(ballBody, cpv(0, 15));
+
+    // Now we create the collision shape for the ball.
+    // You can create multiple collision shapes that point to the same body.
+    // They will all be attached to the body and move around to follow it.
+    cpShape *ballShape = cpSpaceAddShape(space, cpCircleShapeNew(ballBody, radius, cpvzero));
+    cpShapeSetFriction(ballShape, 0.7);
+
+    // Now that it's all set up, we simulate all the objects in the space by
+    // stepping forward through time in small increments called steps.
+    // It is *highly* recommended to use a fixed size time step.
+    cpFloat timeStep = 1.0/60.0;
+    for(cpFloat time = 0; time < 2; time += timeStep){
+        cpVect pos = cpBodyGetPos(ballBody);
+        cpVect vel = cpBodyGetVel(ballBody);
+        printf("Time is %5.2f. ballBody is at (%5.2f, %5.2f). "
+               "It's velocity is (%5.2f, %5.2f)\n",
+                time, pos.x, pos.y, vel.x, vel.y);
+
+        cpSpaceStep(space, timeStep);
+    }
+
+    // Clean up our objects and exit!
+    cpShapeFree(ballShape);
+    cpBodyFree(ballBody);
+    cpShapeFree(ground);
+    cpSpaceFree(space);
+
+    return 0;
+}