Hi, First, thank for this great library, it's really helpful! <p

cute_2d c2PolytoPolyManifold issue about cute_headers HOT 2 CLOSED

Xfennec commented on May 17, 2024

cute_2d c2PolytoPolyManifold issue

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Comments (2)

RandyGaul commented on May 17, 2024

You'll need to get the vertices in CCW order and also set the normals for each polygon. The easiest way is to call c2MakePoly after assigning vertices in any order. So, try this:

c2Poly poly_world;
poly_world.count = 4;
poly_world.verts[0] = c2V(-1.0, -1.0);
poly_world.verts[1] = c2V(1.0, -1.0);
poly_world.verts[2] = c2V(1.0, 1.0);
poly_world.verts[3] = c2V(-1.0, 1.0);
c2MakePoly(&poly_world);

c2Poly poly_car;
poly_car.count = 4;
poly_car.verts[0] = c2V(-0.05, -1.04);
poly_car.verts[1] = c2V(0.05, -1.04);
poly_car.verts[2] = c2V(0.05, -0.94);
poly_car.verts[3] = c2V(-0.05, -0.94);
c2MakePoly(&poly_car);

int res = c2PolytoPoly(&poly_car, NULL, &poly_world, NULL);
printf("res: %d\n", res);

c2Manifold m;
c2PolytoPolyManifold(&poly_car, NULL, &poly_world, NULL, &m);
printf("m.count: %d\n", m.count);

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Xfennec commented on May 17, 2024

Thanks, it does the trick!

May I suggest a short note about this in the doc of c2PolytoPolyManifold?

Subsidiary question: when I fix the winding "by hand", the resulting manifolds are less consistent than when I call c2MakePoly. Does this function does some other "magic" on the poly? (I would like to avoid calling it every frame for every car)

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