import old collision detection code

src/collider/collider.h

@@ -108,9 +108,9 @@ Struct(CLD_GjkData)
   CLD_MenkowskiSimplex simplex;
   Vec2 final_dir;
 
-  // If 1, simplex represents triangle inside of CLD_Menkowski difference
+  // If 1, simplex represents triangle inside of menkowski difference
   // encapsulating the origin. If 0, simplex represents the closest
-  // feature on CLD_Menkowski difference to the origin.
+  // feature on menkowski difference to the origin.
   b32 overlapping;
 
 #if COLLIDER_DEBUG
@@ -124,7 +124,7 @@ Struct(CLD_GjkData)
 Struct(CLD_EpaData)
 {
   Vec2 normal;
-  CLD_MenkowskiFeature closest_feature;  // Represents closest feature (edge or point) to origin on CLD_Menkowski difference
+  CLD_MenkowskiFeature closest_feature;  // Represents closest feature (edge or point) to origin on menkowski difference
 
 #if COLLIDER_DEBUG
   CLD_Prototype prototype;

src/gpu/gpu_dx12/gpu_dx12_core.c

@@ -947,7 +947,7 @@ G_ResourceHandle G_PushResource(G_ArenaHandle arena_handle, G_CommandListHandle
     d3d_desc.Dimension             = D3D12_RESOURCE_DIMENSION_BUFFER;
     d3d_desc.Layout                = D3D12_TEXTURE_LAYOUT_ROW_MAJOR;
     d3d_desc.Format                = DXGI_FORMAT_UNKNOWN;
-    d3d_desc.Width                 = AlignU64(MaxU64(desc.buffer.size, min_buffer_size), 4);
+    d3d_desc.Width                 = AlignU64ToNextPow2(MaxU64(desc.buffer.size, min_buffer_size));
     d3d_desc.Height                = 1;
     d3d_desc.DepthOrArraySize      = 1;
     d3d_desc.MipLevels             = 1;

src/pp/pp_sim/pp_sim_core.c

@@ -153,32 +153,12 @@ S_Shape S_MulXformShape(Xform xf, S_Shape shape)
   return result;
 }
 
-Vec2 S_SupportPointFromShape(S_Shape shape, Vec2 dir)
-{
-  // FIXME: Properly handle rounded polygons
-  Vec2 result = Zi;
-  Vec2 dir_norm = NormVec2(dir);
-  f32 max_dot = -Inf;
-  for (i32 i = 0; i < shape.points_count; ++i)
-  {
-    Vec2 p = shape.points[i];
-    f32 dot = DotVec2(p, dir_norm);
-    if (dot > max_dot)
-    {
-      max_dot = dot;
-      result = p;
-    }
-  }
-  result = AddVec2(result, MulVec2(dir_norm, shape.radius));
-  return result;
-}
-
 Rng2 S_BoundingBoxFromShape(S_Shape shape)
 {
-  Vec2 left = S_SupportPointFromShape(shape, VEC2(-1, 0));
+  Vec2 left = S_SupportPointFromShape(shape, VEC2(-1, 0)).p;
-  Vec2 top = S_SupportPointFromShape(shape, VEC2(0, -1));
+  Vec2 top = S_SupportPointFromShape(shape, VEC2(0, -1)).p;
-  Vec2 right = S_SupportPointFromShape(shape, VEC2(1, 0));
+  Vec2 right = S_SupportPointFromShape(shape, VEC2(1, 0)).p;
-  Vec2 bottom = S_SupportPointFromShape(shape, VEC2(0, 1));
+  Vec2 bottom = S_SupportPointFromShape(shape, VEC2(0, 1)).p;
 
   Rng2 result = Zi;
   result.p0 = VEC2(left.x, top.y);
@@ -186,6 +166,673 @@ Rng2 S_BoundingBoxFromShape(S_Shape shape)
   return result;
 }
 
+
+////////////////////////////////////////////////////////////
+//~ Collision
+
+// NOTE: Everything here is pretty much copied directly from the old physics
+// prototype. It's slow and does more than what we need. For example we should
+// probably just switch from GJK to SAT for shape collision testing.
+
+S_SupportPoint S_SupportPointFromShapeEx(S_Shape shape, Vec2 dir, i32 ignore_idx)
+{
+  S_SupportPoint result = Zi;
+  Vec2 dir_norm = NormVec2(dir);
+  f32 max_dot = -Inf;
+  if (shape.points_count == 1)
+  {
+    // Don't ignore for single-point colliders
+    ignore_idx = -1;
+  }
+  for (i32 point_idx = 0; point_idx < shape.points_count; ++point_idx)
+  {
+    if (point_idx != ignore_idx)
+    {
+      Vec2 p = shape.points[point_idx];
+      f32 dot = DotVec2(p, dir_norm);
+      if (dot > max_dot)
+      {
+        max_dot = dot;
+        result.p = p;
+        result.id = point_idx;
+      }
+    }
+  }
+  result.p = AddVec2(result.p, MulVec2(dir_norm, shape.radius));
+  return result;
+}
+
+S_SupportPoint S_SupportPointFromShape(S_Shape shape, Vec2 dir)
+{
+  return S_SupportPointFromShapeEx(shape, dir, -1);
+}
+
+S_MenkowskiPoint S_MenkowskiPointFromShapes(S_Shape shape0, S_Shape shape1, Vec2 dir)
+{
+  S_MenkowskiPoint result = Zi;
+  result.s0 = S_SupportPointFromShape(shape0, dir);
+  result.s1 = S_SupportPointFromShape(shape1, NegVec2(dir));
+  result.p = SubVec2(result.s0.p, result.s1.p);
+  return result;
+}
+
+S_ClippedLine S_ClipLineToLine(Vec2 a0, Vec2 b0, Vec2 a1, Vec2 b1, Vec2 normal)
+{
+  Vec2 vab0 = SubVec2(b0, a0);
+  Vec2 vab1 = SubVec2(b1, a1);
+  Vec2 va0a1 = SubVec2(a1, a0);
+  Vec2 vb0b1 = SubVec2(b1, b0);
+  f32 vab0_w = WedgeVec2(vab0, normal);
+  f32 vab1_w = WedgeVec2(vab1, normal);
+  f32 va0a1_w = WedgeVec2(va0a1, normal);
+  f32 vb0b1_w = WedgeVec2(vb0b1, normal);
+
+  // FIXME: Handle 0 denominator
+  f32 a0t;
+  f32 b0t;
+  {
+    f32 w = 1 / vab0_w;
+    a0t = ClampF32(va0a1_w * w, 0, 1);
+    b0t = ClampF32(vb0b1_w * -w, 0, 1);
+  }
+  f32 a1t;
+  f32 b1t;
+  {
+    f32 w = 1 / vab1_w;
+    a1t = ClampF32(-va0a1_w * w, 0, 1);
+    b1t = ClampF32(-vb0b1_w * -w, 0, 1);
+  }
+
+  S_ClippedLine result = Zi;
+  result.a0_clipped = AddVec2(a0, MulVec2(vab0, a0t));
+  result.a1_clipped = AddVec2(a1, MulVec2(vab1, a1t));
+  result.b0_clipped = AddVec2(b0, MulVec2(vab0, -b0t));
+  result.b1_clipped = AddVec2(b1, MulVec2(vab1, -b1t));
+  return result;
+}
+
+Vec2 S_ClipPointToLine(Vec2 a, Vec2 b, Vec2 p, Vec2 normal)
+{
+  Vec2 vab = SubVec2(b, a);
+  Vec2 vap = SubVec2(p, a);
+
+  f32 vab_w = WedgeVec2(vab, normal);
+  f32 vap_w = WedgeVec2(vap, normal);
+
+  f32 t;
+  {
+    f32 w = 1 / vab_w;
+    t = ClampF32(vap_w * w, 0, 1);
+  }
+
+  Vec2 result = AddVec2(a, MulVec2(vab, t));
+  return result;
+}
+
+S_CollisionData S_CollisionDataFromShapes(S_Shape shape0, S_Shape shape1)
+{
+  S_CollisionData result = Zi;
+  TempArena scratch = BeginScratchNoConflict();
+
+  f32 tolerance = 0.005f;  // How close can non-overlapping shapes be before collision is considered
+  f32 min_unique_pt_dist_sq = (0.001f * 0.001f);  // NOTE: Should always be less than tolerance, since colliding = 1 if origin is within this distance.
+  u32 max_iterations = 64;  // To prevent extremely large prototypes when origin is in exact center of rounded feature
+
+  //////////////////////////////
+  //- GJK
+
+  S_MenkowskiSimplex simplex = Zi;
+  Vec2 non_overlapping_dir = Zi;
+  b32 is_overlapping = 0;
+  {
+    S_MenkowskiPoint m = Zi;
+
+    // First point is support point in shape's general directions to eachother
+    Vec2 dir = SubVec2(shape1.centroid, shape0.centroid);
+    if (IsVec2Zero(dir)) dir = VEC2(1, 0);
+    simplex.a = S_MenkowskiPointFromShapes(shape0, shape1, dir);
+    simplex.count = 1;
+
+    Vec2 removed_a = Zi;
+    Vec2 removed_b = Zi;
+    u32 num_removed = 0;
+    for (;;)
+    {
+      //////////////////////////////
+      //- Find initial points in simplex
+
+      if (simplex.count == 1)
+      {
+        // Second point is support point towards origin
+        dir = NegVec2(simplex.a.p);
+
+        m = S_MenkowskiPointFromShapes(shape0, shape1, dir);
+        // Check that new point is far enough away from existing point
+        if (Vec2LenSq(SubVec2(m.p, simplex.a.p)) < min_unique_pt_dist_sq)
+        {
+          is_overlapping = 0;
+          break;
+        }
+        simplex.b = simplex.a;
+        simplex.a = m;
+        simplex.count = 2;
+
+        // Third point is support point in direction of line normal towards origin
+        dir = PerpVec2TowardsDir(SubVec2(simplex.b.p, simplex.a.p), NegVec2(simplex.a.p));
+      }
+
+      //////////////////////////////
+      //- Find third piont in simplex
+
+      {
+        m = S_MenkowskiPointFromShapes(shape0, shape1, dir);
+        // Check that new point is far enough away from existing points
+        if (
+          Vec2LenSq(SubVec2(m.p, simplex.a.p)) < min_unique_pt_dist_sq ||
+          Vec2LenSq(SubVec2(m.p, simplex.b.p)) < min_unique_pt_dist_sq || (
+            (num_removed >= 1) && (
+              (Vec2LenSq(SubVec2(m.p, removed_a)) < min_unique_pt_dist_sq) ||
+              (num_removed >= 2 && Vec2LenSq(SubVec2(m.p, removed_b)) < min_unique_pt_dist_sq)
+            )
+          ) ||
+          AbsF32(WedgeVec2(SubVec2(simplex.b.p, simplex.a.p), SubVec2(m.p, simplex.a.p))) < min_unique_pt_dist_sq
+        )
+        {
+          is_overlapping = 0;
+          break;
+        }
+        simplex.c = simplex.b;
+        simplex.b = simplex.a;
+        simplex.a = m;
+        simplex.count = 3;
+
+        if (
+          (AbsF32(WedgeVec2(SubVec2(simplex.b.p, simplex.a.p), NegVec2(simplex.a.p))) <= min_unique_pt_dist_sq) ||
+          (AbsF32(WedgeVec2(SubVec2(simplex.c.p, simplex.b.p), NegVec2(simplex.b.p))) <= min_unique_pt_dist_sq) ||
+          (AbsF32(WedgeVec2(SubVec2(simplex.c.p, simplex.a.p), NegVec2(simplex.a.p))) <= min_unique_pt_dist_sq)
+        )
+        {
+          // Simplex lies on origin
+          is_overlapping = 1;
+          break;
+        }
+      }
+
+      //////////////////////////////
+      //- Determine origin region
+
+      Vec2 vab = SubVec2(simplex.b.p, simplex.a.p);
+      Vec2 vac = SubVec2(simplex.c.p, simplex.a.p);
+      Vec2 vbc = SubVec2(simplex.c.p, simplex.b.p);
+
+      Vec2 rab_dir = PerpVec2TowardsDir(vab, NegVec2(vac));
+      Vec2 rac_dir = PerpVec2TowardsDir(vac, NegVec2(vab));
+      Vec2 rbc_dir = PerpVec2TowardsDir(vbc, vab);
+
+      f32 rab_dot = DotVec2(rab_dir, NegVec2(simplex.a.p));
+      f32 rac_dot = DotVec2(rac_dir, NegVec2(simplex.a.p));
+      f32 rbc_dot = DotVec2(rbc_dir, NegVec2(simplex.b.p));
+
+      f32 vab_dot = DotVec2(vab, NegVec2(simplex.a.p)) / Vec2LenSq(vab);
+      f32 vac_dot = DotVec2(vac, NegVec2(simplex.a.p)) / Vec2LenSq(vac);
+      f32 vbc_dot = DotVec2(vbc, NegVec2(simplex.b.p)) / Vec2LenSq(vbc);
+
+      if (rab_dot >= 0 && vab_dot >= 0 && vab_dot <= 1)
+      {
+        // Region ab, remove c
+        num_removed = 1;
+        removed_a = simplex.c.p;
+        simplex.count = 2;
+        dir = rab_dir;  // Next third point is in direction of region ab
+      }
+      else if (rac_dot >= 0 && vac_dot >= 0 && vac_dot <= 1)
+      {
+        // Region ac, remove b
+        num_removed = 1;
+        removed_a = simplex.b.p;
+        simplex.count = 2;
+        simplex.b = simplex.c;
+        dir = rac_dir;  // Next third point is in direction of region ac
+      }
+      else if (rbc_dot >= 0 && vbc_dot >= 0 && vbc_dot <= 1)
+      {
+        // Region bc, remove a
+        num_removed = 1;
+        removed_a = simplex.a.p;
+        simplex.count = 2;
+        simplex.a = simplex.b;
+        simplex.b = simplex.c;
+        dir = rbc_dir;  // Next third point is in direction of region bc
+      }
+      else if (vab_dot <= 0 && vac_dot <= 0)
+      {
+        // Region a, remove bc
+        num_removed = 2;
+        removed_a = simplex.b.p;
+        removed_b = simplex.c.p;
+        simplex.count = 1;
+      }
+      else if (vab_dot >= 1 && vbc_dot <= 0)
+      {
+        // Region b, remove ac
+        num_removed = 2;
+        removed_a = simplex.a.p;
+        removed_b = simplex.c.p;
+        simplex.count = 1;
+        simplex.a = simplex.b;
+      }
+      else if (vac_dot >= 1 && vbc_dot >= 1)
+      {
+        // Region c, remove ab
+        num_removed = 2;
+        removed_a = simplex.a.p;
+        removed_b = simplex.b.p;
+        simplex.count = 1;
+        simplex.a = simplex.c;
+      }
+      else
+      {
+        // No region, must be in simplex
+        is_overlapping = 1;
+        break;
+      }
+    }
+    if (!is_overlapping)
+    {
+      non_overlapping_dir = dir;
+    }
+  }
+
+  //////////////////////////////
+  //- EPA
+
+  Vec2 normal = Zi;
+  S_MenkowskiSimplex closest_feature = Zi;
+  {
+    S_MenkowskiPoint *proto = 0;
+    u32 proto_count = 0;
+    if (is_overlapping)
+    {
+      proto = ArenaNext(scratch.arena, S_MenkowskiPoint);
+      {
+        Assert(simplex.count == 3);
+        S_MenkowskiPoint *tmp = PushStructsNoZero(scratch.arena, S_MenkowskiPoint, 3);
+        tmp[0] = simplex.a;
+        tmp[1] = simplex.b;
+        tmp[2] = simplex.c;
+        proto_count = 3;
+      }
+
+      i32 winding = WindingFromVec2(SubVec2(simplex.c.p, simplex.a.p), SubVec2(simplex.b.p, simplex.a.p));
+
+      u32 epa_iterations = 0;
+      for (;;)
+      {
+        ++epa_iterations;
+
+        // Find dir from origin to closest edge
+        // FIXME: Winding order of ps & pe index
+        f32 closest_len_sq = Inf;
+        S_MenkowskiPoint closest_a = Zi;
+        S_MenkowskiPoint closest_b = Zi;
+        u32 closest_b_index = 0;
+        for (u32 i = 0; i < proto_count; ++i)
+        {
+          u32 a_index = i;
+          u32 b_index = (i < proto_count - 1) ? (i + 1) : 0;
+          S_MenkowskiPoint a = proto[a_index];
+          S_MenkowskiPoint b = proto[b_index];
+
+          Vec2 vab = SubVec2(b.p, a.p);
+          Vec2 vao = NegVec2(a.p);
+
+          f32 proj_ratio = ClampF32(DotVec2(vao, vab) / Vec2LenSq(vab), 0, 1);
+          Vec2 proj = AddVec2(a.p, MulVec2(vab, proj_ratio));
+
+          f32 proj_len_sq = Vec2LenSq(proj);
+          if (proj_len_sq < closest_len_sq - min_unique_pt_dist_sq)
+          {
+            closest_a = a;
+            closest_b = b;
+            closest_b_index = b_index;
+            closest_len_sq = proj_len_sq;
+          }
+        }
+        Vec2 vab = SubVec2(closest_b.p, closest_a.p);
+
+        // Find new point in dir
+        Vec2 dir = MulVec2(PerpVec2(vab), winding);
+        S_MenkowskiPoint m = S_MenkowskiPointFromShapes(shape0, shape1, dir);
+
+        // if (debug)
+        // {
+        //   // If debug step count is reached, we still want to inspect the normal at the step
+        //   normal = NormVec2(dir);
+        //   closest_feature.a = closest_a;
+        //   closest_feature.b = closest_b;
+        //   closest_feature.count = 2;
+        // }
+
+        // Check validity of new point
+        {
+          b32 valid = 1;
+
+          {
+            // NOTE: Changing this value affects how stable normals are for circular colliders
+            //const f32 validity_epsilon = min_unique_pt_dist_sq;  // Arbitrary
+            //const f32 validity_epsilon = 0.00000000001f;  // Arbitrary
+            const f32 validity_epsilon = min_unique_pt_dist_sq;  // Arbitrary
+
+            Vec2 vam = SubVec2(m.p, closest_a.p);
+            Vec2 vbm = SubVec2(closest_b.p, closest_a.p);
+
+            f32 dot = DotVec2(vab, vam) / Vec2LenSq(vab);
+
+            if (dot >= -validity_epsilon && dot <= 1 - validity_epsilon && (WedgeVec2(vab, vam) * -winding) >= -validity_epsilon)
+            {
+              // New point is not between edge
+              valid = 0;
+            }
+            else if (Vec2LenSq(vam) < min_unique_pt_dist_sq || Vec2LenSq(vbm) < min_unique_pt_dist_sq)
+            {
+              // New point is too close to existing
+              valid = 0;
+            }
+          }
+
+          if (!valid || epa_iterations >= max_iterations)
+          {
+            normal = NormVec2(dir);
+            closest_feature.a = closest_a;
+            closest_feature.b = closest_b;
+            closest_feature.count = 2;
+            break;
+          }
+        }
+
+        // Expand prototype
+        PushStructNoZero(scratch.arena, S_MenkowskiPoint);
+        ++proto_count;
+
+        // Shift points in prototype to make room
+        for (u32 i = proto_count - 1; i > closest_b_index; --i)
+        {
+          u32 shift_from = (i > 0) ? i - 1 : proto_count - 1;
+          u32 shift_to = i;
+          proto[shift_to] = proto[shift_from];
+        }
+
+        // Insert new point into prototype
+        proto[closest_b_index] = m;
+      }
+    }
+    else
+    {
+      normal = NormVec2(non_overlapping_dir);
+      closest_feature.count = simplex.count;
+      closest_feature.a = simplex.a;
+      closest_feature.b = simplex.b;
+    }
+  }
+
+  //////////////////////////////
+  //- Determine collision
+
+  b32 is_colliding = 0;
+  {
+    if (is_overlapping)
+    {
+      is_colliding = 1;
+    }
+    else
+    {
+      // Shapes not overlapping, determine if distance between shapes within tolerance
+      if (closest_feature.count == 1)
+      {
+        Vec2 p = NegVec2(closest_feature.a.p);
+        if (Vec2LenSq(p) <= (tolerance * tolerance))
+        {
+          is_colliding = 1;
+        }
+      }
+      else
+      {
+        // Project origin to determine if distance is within tolerance.
+        Assert(closest_feature.count == 2);
+        Vec2 vab = SubVec2(closest_feature.b.p, closest_feature.a.p);
+        Vec2 vao = NegVec2(closest_feature.a.p);
+        f32 ratio = ClampF32(DotVec2(vab, vao) / DotVec2(vab, vab), 0, 1);
+        Vec2 p = AddVec2(closest_feature.a.p, MulVec2(vab, ratio));
+        if (Vec2LenSq(p) <= (tolerance * tolerance))
+        {
+          is_colliding = 1;
+        }
+      }
+    }
+  }
+
+  //////////////////////////////
+  //- Compute collision points
+
+  // Clip to determine final points
+  i32 collision_points_count = 0;
+  S_CollisionPoint collision_points[2] = Zi;
+  if (is_colliding)
+  {
+    // Max vertices must be < 16 to fit in 4 bit ids
+    StaticAssert(countof(shape0.points) <= 16);
+    {
+      b32 collapse0 = 0;
+      b32 collapse1 = 0;
+
+      S_SupportPoint a0 = closest_feature.a.s0;
+      S_SupportPoint a1 = closest_feature.a.s1;
+      S_SupportPoint b0 = closest_feature.b.s0;
+      S_SupportPoint b1 = closest_feature.b.s1;
+      // FIXME: Manually account for shapes w/ 1 & 2 points
+      if (closest_feature.count == 2)
+      {
+        if (a0.id == b0.id)
+        {
+          if (shape0.points_count > 1)
+          {
+            b0 = S_SupportPointFromShapeEx(shape0, normal, b0.id);
+          }
+          else
+          {
+            collapse0 = 1;
+            b0 = a0;
+          }
+        }
+        if (a1.id == b1.id)
+        {
+          if (shape1.points_count > 1)
+          {
+            b1 = S_SupportPointFromShapeEx(shape1, NegVec2(normal), b1.id);
+          }
+          else
+          {
+            collapse1 = 1;
+            b1 = a1;
+          }
+        }
+      }
+      else
+      {
+        collapse0 = 1;
+        collapse1 = 1;
+        b0 = a0;
+        b1 = a1;
+      }
+
+      Vec2 vab0 = SubVec2(b0.p, a0.p);
+      Vec2 vab1 = SubVec2(b1.p, a1.p);
+      Vec2 vab0_norm = NormVec2(vab0);
+      Vec2 vab1_norm = NormVec2(vab1);
+
+      // Swap points based on normal direction for consistent clipping
+      if (WedgeVec2(normal, vab0) < 0)
+      {
+        S_SupportPoint tmp = a0;
+        a0 = b0;
+        b0 = tmp;
+        vab0 = NegVec2(vab0);
+      }
+      if (WedgeVec2(normal, vab1) < 0)
+      {
+        S_SupportPoint tmp = a1;
+        a1 = b1;
+        b1 = tmp;
+        vab1 = NegVec2(vab1);
+      }
+
+      // Collapse lines that are too far in the direction of the normal to be accurately clipped
+      f32 collapse_epsilon = 0.05f;
+      collapse0 = collapse0 || AbsF32(WedgeVec2(normal, vab0_norm)) < collapse_epsilon;
+      collapse1 = collapse1 || AbsF32(WedgeVec2(normal, vab1_norm)) < collapse_epsilon;
+
+      // Collapse lines into deepest point
+      if (collapse0)
+      {
+        if (DotVec2(normal, vab0) > 0)
+        {
+          a0 = b0;
+        }
+        else
+        {
+          // TODO: Remove this (debugging)
+          b0 = a0;
+        }
+      }
+      if (collapse1)
+      {
+        if (DotVec2(normal, vab1) < 0)
+        {
+          a1 = b1;
+        }
+        else
+        {
+          // TODO: Remove this (debugging)
+          b1 = a1;
+        }
+      }
+
+      f32 a_sep = Inf;
+      f32 b_sep = Inf;
+      Vec2 a_midpoint = Zi;
+      Vec2 b_midpoint = Zi;
+      b32 ignore_a = 1;
+      b32 ignore_b = 1;
+      if (!collapse0 && !collapse1)
+      {
+        // Clip line to line
+        S_ClippedLine clip_result = S_ClipLineToLine(a0.p, b0.p, a1.p, b1.p, normal);
+        Vec2 a0_clipped = clip_result.a0_clipped;
+        Vec2 a1_clipped = clip_result.a1_clipped;
+        Vec2 b0_clipped = clip_result.b0_clipped;
+        Vec2 b1_clipped = clip_result.b1_clipped;
+        // Calc midpoint between clipped a & b
+        Vec2 va0a1_clipped = SubVec2(a1_clipped, a0_clipped);
+        Vec2 vb0b1_clipped = SubVec2(b1_clipped, b0_clipped);
+        a_sep = DotVec2(va0a1_clipped, normal);
+        b_sep = DotVec2(vb0b1_clipped, normal);
+        a_midpoint = AddVec2(a0_clipped, MulVec2(va0a1_clipped, 0.5f));
+        b_midpoint = AddVec2(b0_clipped, MulVec2(vb0b1_clipped, 0.5f));
+        ignore_a = 0;
+        ignore_b = 0;
+        Vec2 vfin = SubVec2(b_midpoint, a_midpoint);
+        if (Vec2LenSq(vfin) < (0.005 * 0.005))
+        {
+          if (a_sep > b_sep)
+          {
+            ignore_a = 1;
+          }
+          else
+          {
+            ignore_b = 1;
+          }
+        }
+      }
+      else
+      {
+        Vec2 p0 = a0.p;
+        Vec2 p1 = a1.p;
+        // TODO: Choose ID based on closest clipped point
+        if (collapse1 && !collapse0)
+        {
+          // Project a1 onto vab0
+          p0 = S_ClipPointToLine(a0.p, b0.p, a1.p, normal);
+        }
+        if (collapse0 && !collapse1)
+        {
+          // Project a0 onto vab1
+          p1 = S_ClipPointToLine(a1.p, b1.p, a0.p, normal);
+        }
+        // Calc midpoint
+        Vec2 vsep = SubVec2(p1, p0);
+        a_midpoint = AddVec2(p0, MulVec2(vsep, 0.5f));
+        a_sep = DotVec2(normal, p1) - DotVec2(normal, p0);
+        ignore_a = 0;
+      }
+
+      // Insert points
+      if (!ignore_a && a_sep < tolerance)
+      {
+        S_CollisionPoint *point = &collision_points[collision_points_count++];
+        point->id = a0.id | (a1.id << 4);
+        point->separation = a_sep;
+        point->p = a_midpoint;
+      }
+      if (!ignore_b && b_sep < tolerance)
+      {
+        S_CollisionPoint *point = &collision_points[collision_points_count++];
+        point->id = b0.id | (b1.id << 4);
+        point->separation = b_sep;
+        point->p = b_midpoint;
+      }
+    }
+  }
+
+  //////////////////////////////
+  //- Compute closest points
+
+  Vec2 closest_p0 = Zi;
+  Vec2 closest_p1 = Zi;
+  if (closest_feature.count == 1)
+  {
+    closest_p0 = closest_feature.a.s0.p;
+    closest_p1 = closest_feature.a.s1.p;
+  }
+  else
+  {
+    Assert(closest_feature.count == 2);
+    // FIXME: Winding order dependent?
+    f32 ratio = 0;
+    {
+      // Determine ratio between edge a & b that projected origin lies
+      Vec2 vab = SubVec2(closest_feature.b.p, closest_feature.a.p);
+      Vec2 vao = NegVec2(closest_feature.a.p);
+      ratio = ClampF32(DotVec2(vab, vao) / DotVec2(vab, vab), 0, 1);
+    }
+    // Shape 0
+    closest_p0 = SubVec2(closest_feature.b.s0.p, closest_feature.a.s0.p);
+    closest_p0 = MulVec2(closest_p0, ratio);
+    closest_p0 = AddVec2(closest_p0, closest_feature.a.s0.p);
+    // Shape 1
+    closest_p1 = SubVec2(closest_feature.b.s1.p, closest_feature.a.s1.p);
+    closest_p1 = MulVec2(closest_p1, ratio);
+    closest_p1 = AddVec2(closest_p1, closest_feature.a.s1.p);
+  }
+
+  CopyStructs(result.collision_points, collision_points, countof(collision_points));
+  result.collision_points_count = collision_points_count;
+  result.closest_p0 = closest_p0;
+  result.closest_p1 = closest_p1;
+
+  EndScratch(scratch);
+  return result;
+}
+
 ////////////////////////////////////////////////////////////
 //~ Lookup helpers
 
@@ -594,7 +1241,7 @@ void S_TickForever(WaveLaneCtx *lane)
         test_rect.p1 = VEC2(1, 1);
 
         constraint->shape1 = S_ShapeFromDesc(
-          .radius = 0.2,
+          .radius = 0.5,
           .count = 4,
           .points[0] = VEC2(test_rect.p0.x, test_rect.p0.y),
           .points[1] = VEC2(test_rect.p1.x, test_rect.p0.y),
@@ -653,8 +1300,12 @@ void S_TickForever(WaveLaneCtx *lane)
         Vec2 normal = NormVec2(shape_dir);
         Vec2 neg_normal = NegVec2(normal);
 
-        Vec2 shape0_pt = S_SupportPointFromShape(shape0, shape_dir);
+        // Vec2 shape0_pt = S_SupportPointFromShape(shape0, shape_dir);
-        Vec2 shape1_pt = S_SupportPointFromShape(shape1, neg_shape_dir);
+        // Vec2 shape1_pt = S_SupportPointFromShape(shape1, neg_shape_dir);
+
+        S_CollisionData collision_data = S_CollisionDataFromShapes(shape0, shape1);
+        Vec2 shape0_pt = collision_data.closest_p0;
+        Vec2 shape1_pt = collision_data.closest_p1;
 
         Vec2 sep = SubVec2(shape1_pt, shape0_pt);
         f32 sep_along_normal = DotVec2(sep, normal);
@@ -663,13 +1314,11 @@ void S_TickForever(WaveLaneCtx *lane)
 
         // f32 sep_normal = DotVec2(sep, normal);
 
-
         S_DebugDrawPoint(shape0_pt, Color_Cyan);
         S_DebugDrawPoint(shape1_pt, Color_Cyan);
 
-
+        S_DebugDrawPoint(collision_data.collision_points[0].p, Color_Red);
-
+        S_DebugDrawPoint(collision_data.collision_points[0].p, Color_Red);
-
 
         if (sep_along_normal < 0)
         {
@@ -732,7 +1381,7 @@ void S_TickForever(WaveLaneCtx *lane)
         {
           Vec4 color = VEC4(0.8, 0.8, 0.8, 1);
           Vec2 p0 = world_shape.centroid;
-          Vec2 p1 = S_SupportPointFromShape(world_shape, ent->look);
+          Vec2 p1 = S_SupportPointFromShape(world_shape, ent->look).p;
           S_DebugDrawLine(p0, p1, color);
         }
       }

src/pp/pp_sim/pp_sim_core.h

@@ -110,6 +110,52 @@ Struct(S_EntList)
   u64 count;
 };
 
+////////////////////////////////////////////////////////////
+//~ Collision types
+
+Struct(S_SupportPoint)
+{
+  Vec2 p;
+  i32 id;  // Index of the originating piont in the shape
+};
+
+Struct(S_CollisionPoint)
+{
+  Vec2 p;
+  f32 separation;
+  u32 id;  // Based on polygon edge-to-edge
+};
+
+Struct(S_MenkowskiPoint)
+{
+  Vec2 p;               // Menkowski difference point
+  S_SupportPoint s0;    // Support point of first shape in dir
+  S_SupportPoint s1;    // Support point of second shape in -dir
+};
+
+Struct(S_MenkowskiSimplex)
+{
+  i32 count;
+  S_MenkowskiPoint a, b, c;
+};
+
+Struct(S_ClippedLine)
+{
+  Vec2 a0_clipped, b0_clipped;
+  Vec2 a1_clipped, b1_clipped;
+};
+
+Struct(S_CollisionData)
+{
+  // Contact manifold
+  i32 collision_points_count;
+  S_CollisionPoint collision_points[2];
+
+  // Closest points
+  Vec2 closest_p0;
+  Vec2 closest_p1;
+};
+
 ////////////////////////////////////////////////////////////
 //~ Constraint types
 
@@ -324,10 +370,18 @@ S_Shape S_ShapeFromDescEx(S_ShapeDesc desc);
 #define S_ShapeFromDesc(...) S_ShapeFromDescEx((S_ShapeDesc) { __VA_ARGS__ })
 
 S_Shape S_MulXformShape(Xform xf, S_Shape shape);
-
-Vec2 S_SupportPointFromShape(S_Shape shape, Vec2 dir);
 Rng2 S_BoundingBoxFromShape(S_Shape shape);
 
+////////////////////////////////////////////////////////////
+//~ Collision
+
+S_SupportPoint S_SupportPointFromShapeEx(S_Shape shape, Vec2 dir, i32 ignore_idx);
+S_SupportPoint S_SupportPointFromShape(S_Shape shape, Vec2 dir);
+S_MenkowskiPoint S_MenkowskiPointFromShapes(S_Shape shape0, S_Shape shape1, Vec2 dir);
+S_ClippedLine S_ClipLineToLine(Vec2 a0, Vec2 b0, Vec2 a1, Vec2 b1, Vec2 normal);
+Vec2 S_ClipPointToLine(Vec2 a, Vec2 b, Vec2 p, Vec2 normal);
+S_CollisionData S_CollisionDataFromShapes(S_Shape shape0, S_Shape shape1);
+
 ////////////////////////////////////////////////////////////
 //~ Lookup helpers
 

src/pp/pp_vis/pp_vis_core.c

@@ -191,7 +191,7 @@ void V_DrawShape(S_Shape shape, Vec4 srgb, i32 detail, V_DrawFlag flags)
       {
         f32 rad = ((f32)i / (f32)detail) * Tau;
         Vec2 dir = Vec2FromAngle(rad);
-        Vec2 sp = S_SupportPointFromShape(shape, dir);
+        Vec2 sp = S_SupportPointFromShape(shape, dir).p;
         draw_points.points[i] = sp;
       }
       V_DrawPoly(draw_points, srgb, flags);
@@ -237,8 +237,7 @@ V_WidgetTheme V_GetWidgetTheme(void)
   theme.icon_font = UI_BuiltinIconFont();
 
   // theme.font_size = 14;
-  // theme.font_size = TweakFloat("Font size", 14, 6, 50, .precision = 0);
+  theme.font_size = TweakFloat("Font size", 14, 6, 50, .precision = 0);
-  theme.font_size = TweakFloat("Font size", 14, 6, 50, .precision = 2);
   theme.h1 = 2.00;
   theme.h2 = 1.50;
   theme.h3 = 1.25;
@@ -247,8 +246,6 @@ V_WidgetTheme V_GetWidgetTheme(void)
   theme.h6 = 0.75;
   theme.micro = 0.50;
 
-  // theme.rounding = 0;
-  // theme.rounding = 1;
   theme.rounding = TweakFloat("Rounding", 1, 0, 1);
 
   theme.text_padding_x = 5;
@@ -1511,7 +1508,7 @@ void V_TickForever(WaveLaneCtx *lane)
         UI_Push(BorderColor, window_border_color);
         // UI_Push(BorderSize, theme.window_bd_sz);
         UI_Push(BorderSize, 1);
-        UI_Push(Rounding, UI_RGROW(0.095 * theme.rounding));
+        UI_Push(Rounding, UI_RGROW(0.06 * theme.rounding));
         UI_Push(Width, UI_FNT(40, 0));
         UI_Push(Height, UI_SHRINK(0, 0));
         UI_Push(ChildLayoutAxis, Axis_Y);
@@ -1707,28 +1704,6 @@ void V_TickForever(WaveLaneCtx *lane)
                       String new_tweak_str = tweak_var.value;
                       b32 is_default = MatchString(new_tweak_str, tweak_var.initial);
 
-                      // Tweak label
-                      {
-                        UI_BuildSpacer(UI_PIX(spacing, 1), Axis_X);
-                        if (is_default)
-                        {
-                          UI_SetNext(TextColor, theme.col.hint);
-                          UI_SetNext(FontSize, UI_Top(FontSize) * theme.h5);
-                        }
-                        else
-                        {
-                          UI_SetNext(TextColor, Color_White);
-                        }
-                        UI_SetNext(ChildAlignment, UI_Region_Left);
-                        UI_SetNext(Width, UI_SHRINK(0, 1));
-                        UI_SetNext(Height, UI_SHRINK(0, 1));
-                        UI_SetNext(Text, new_tweak_str);
-                        UI_SetNext(Flags, UI_BoxFlag_DrawText);
-                        UI_SetNext(BackgroundColor, 0);
-                        UI_SetNext(BorderColor, 0);
-                        UI_BuildBox();
-                      }
-
                       // Reset button
                       if (!is_default)
                       {
@@ -1769,6 +1744,28 @@ void V_TickForever(WaveLaneCtx *lane)
                         UI_BuildIconEx(reset_key, theme.icon_font, UI_Icon_Loop2);
                       }
 
+                      // Tweak label
+                      {
+                        UI_BuildSpacer(UI_PIX(spacing, 1), Axis_X);
+                        if (is_default)
+                        {
+                          UI_SetNext(TextColor, theme.col.hint);
+                        }
+                        else
+                        {
+                          UI_SetNext(TextColor, Color_White);
+                        }
+                        UI_SetNext(FontSize, UI_Top(FontSize) * theme.h5);
+                        UI_SetNext(ChildAlignment, UI_Region_Left);
+                        UI_SetNext(Width, UI_SHRINK(0, 1));
+                        UI_SetNext(Height, UI_SHRINK(0, 1));
+                        UI_SetNext(Text, new_tweak_str);
+                        UI_SetNext(Flags, UI_BoxFlag_DrawText | UI_BoxFlag_NoTextTruncation);
+                        UI_SetNext(BackgroundColor, 0);
+                        UI_SetNext(BorderColor, 0);
+                        UI_BuildBox();
+                      }
+
                       UI_BuildSpacer(UI_PIX(spacing, 1), Axis_X);
 
                       switch (tweak_var.kind)
@@ -2299,7 +2296,7 @@ void V_TickForever(WaveLaneCtx *lane)
           S_Ent *ent = &cmd->ent;
           *ent = *S_EntFromKey(&V.lookup, V.player_key);
           ent->key = V.player_key;
-          ent->move_speed = 0.1;
+          ent->move_speed = 0.05;
           ent->local_shape = S_ShapeFromDesc(
             .mass = 10,
             .count = 1,