Fix various cases of bad math

[libs/game.git] / examples / bassteroids / source / physics.cpp

diff --git a/examples/bassteroids/source/physics.cpp b/examples/bassteroids/source/physics.cpp
index 612a3ece9bde82edb6cdf23fbef3b2b7fc0a248b..67cdf6fe596bbf29199b7af96174c92eecaefc92 100644 (file)
--- a/examples/bassteroids/source/physics.cpp
+++ b/examples/bassteroids/source/physics.cpp
@@ -186,7 +186,9 @@ void Physics::apply_impulses()
                LinAl::Vector<float, 2> v_p1 = entity1.velocity+LinAl::Vector<float, 2>(-r1.y, r1.x)*entity1.angular_velocity.radians();
                LinAl::Vector<float, 2> v_p2 = entity2.velocity+LinAl::Vector<float, 2>(-r2.y, r2.x)*entity2.angular_velocity.radians();
                LinAl::Vector<float, 2> v_rel = v_p2-v_p1;
-               LinAl::Vector<float, 2> tangent = normalize(v_rel-c.normal*inner_product(v_rel, c.normal));
+               LinAl::Vector<float, 2> tangent = v_rel-c.normal*inner_product(v_rel, c.normal);
+               float v_tan = tangent.norm();
+               tangent = (v_tan>1e-5 ? normalize(tangent) : LinAl::Vector<float, 2>(-c.normal.y, c.normal.x));
                float restitution = 1.0f;
                float friction_coeff = 0.1f;
                float inv_mass_sum = entity1.inverse_mass+entity2.inverse_mass;
@@ -249,11 +251,29 @@ void Physics::collide_circle_box(unsigned i, unsigned j)
        LinAl::Vector<float, 2> local_closest(clamp(local_delta.x, -half_size.x, half_size.x), clamp(local_delta.y, -half_size.y, half_size.y));
        LinAl::Vector<float, 2> local_cdelta = local_delta-local_closest;
        float d_sq = inner_product(local_cdelta, local_cdelta);
+
        if(d_sq<radius*radius)
        {
                Collision &collision = get_collision(i, j);
-               collision.normal = normalize(LinAl::Vector<float, 2>(c*local_cdelta.x-s*local_cdelta.y, c*local_cdelta.y+s*local_cdelta.x));
-               collision.depth = radius-sqrt(d_sq);
+               if(d_sq>1e-10)
+               {
+                       collision.normal = normalize(LinAl::Vector<float, 2>(c*local_cdelta.x-s*local_cdelta.y, c*local_cdelta.y+s*local_cdelta.x));
+                       collision.depth = radius-sqrt(d_sq);
+               }
+               else
+               {
+                       LinAl::Vector<float, 2> inside_dist(half_size.x-abs(local_delta.x), half_size.y-abs(local_delta.y));
+                       if(inside_dist.x<inside_dist.y)
+                       {
+                               collision.normal = LinAl::Vector<float, 2>(c, s) * (local_delta.x<0 ? -1.0f : 1.0f);
+                               collision.depth = radius+inside_dist.x;
+                       }
+                       else
+                       {
+                               collision.normal = LinAl::Vector<float, 2>(-s, c) * (local_delta.y<0 ? -1.0f : 1.0f);
+                               collision.depth = radius+inside_dist.y;
+                       }
+               }
                collision.point = pos1-collision.normal*(radius-collision.depth/2);
                if(collision.body1!=i)
                        collision.normal = -collision.normal;