VelocityRaptor

A programming exercise to make a physics engine. The design and math is due mostly to Erin Catto, and his "Fast and Simple Physics using Sequential Impulses" and "Physics for Game Programmers Talk". For Collision Detection, credit to Dyn4J for best Separate Axis Theorem explanation I've seen, http://www.dyn4j.org/2010/01/sat/

It features Collision detection for convex polygons with the Separate Axis Theorum, and it can support concanve shapes, by using ear clipping to turn concave shapes into triangles. Collision's are resolved with impulses. Units are in pixels.

##Projects Using Velocity Raptor

Crown Room

Chicken Coup

Topdown Shooter

##Velocity Raptor Demo videos

Velocity Raptor Benchmark and Joints

Velocity Raptor Fluids

Velocity Raptor concave and composite polyons

##Usage

To create a world:

vrWorld* world = vrWorldInit(vrWorldAlloc());
world->gravity = vrVect(0, 9.81);

To add a body:

vrRigidBody* body = vrBodyInit(vrBodyAlloc());
body->bodyMaterial.mass = 5;
body->bodyMaterial.invMass = 1.0 / body->bodyMaterial.mass;
body->bodyMaterial.momentInertia = vrMomentForBox(10, 10, body->bodyMaterial.mass);
body->bodyMaterial.invMomentInertia = 1.0 / body->bodyMaterial.momentInertia;
body->bodyMaterial.friction = 0.01;
body->bodyMaterial.restitution = 0.2;
vrWorldAddBody(world, body);

To add a box shape:

vrShape* shape = vrShapeInit(vrShapeAlloc());
shape = vrShapePolyInit(shape);
shape->shape = vrPolyBoxInit(shape->shape, x, y, w, h);
vrArrayPush(body->shape, shape);

To add a polygon shape:

vrShape* shape = vrShapeInit(vrShapeAlloc());
shape = vrShapePolyInit(shape);
vrAddVertexToPolyShape(shape->shape, vrVect(0, 0));
vrAddVertexToPolyShape(shape->shape, vrVect(10, 0));
vrAddVertexToPolyShape(shape->shape, vrVect(10, 10));
vrAddVertexToPolyShape(shape->shape, vrVect(0, 10));
vrArrayPush(body->shape, shape);

To add a circle shape:

vrShape* shape = vrShapeInit(vrShapeAlloc());
shape = vrShapeCircleInit(shape);
shape->shape = vrCircleInit(shape->shape);
vrCircleShape* circle = shape->shape;
circle->center = vrVect(0, 0);
circle->radius = 25;
vrArrayPush(body->shape, shape);

Every tick, call this to update the world:

vrWorldStep(world);

To clean up, and free all memory:

vrWorldDestroy(world);

To remove a body from the world and free its memory before destruction of world

vrWorldRemoveBody(world, body);