From 660a535a7c890081bedb3c25c306969a167802db Mon Sep 17 00:00:00 2001
From: sergeypdev <sergeypoznyak@protonmail.com>
Date: Sat, 1 Feb 2025 01:07:18 +0400
Subject: [PATCH] Experiment with different com calculations

---
 game/assets/assets.odin | 16 +++++++++++++---
 game/game.odin          |  3 ++-
 game/physics/scene.odin |  2 ++
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/game/assets/assets.odin b/game/assets/assets.odin
index 4e072da..1deebb7 100644
--- a/game/assets/assets.odin
+++ b/game/assets/assets.odin
@@ -33,8 +33,9 @@ Loaded_BVH :: struct {
 }
 
 Loaded_Convex :: struct {
-	mesh:           collision.Convex,
-	center_of_mass: rl.Vector3,
+	mesh:                collision.Convex,
+	center_of_mass:      rl.Vector3,
+	center_of_mass_tris: rl.Vector3,
 }
 
 destroy_loaded_bvh :: proc(loaded_bvh: Loaded_BVH) {
@@ -363,6 +364,7 @@ get_convex :: proc(assetman: ^Asset_Manager, path: cstring) -> (result: Loaded_C
 	center /= f32(len(vertices))
 
 	center_of_mass: rl.Vector3
+	center_of_mass_tris: rl.Vector3
 
 	mesh := halfedge.Half_Edge_Mesh {
 		vertices = vertices[:],
@@ -373,6 +375,7 @@ get_convex :: proc(assetman: ^Asset_Manager, path: cstring) -> (result: Loaded_C
 
 	// Center of mass calculation
 	total_volume := f32(0.0)
+	total_area_tris := f32(0.0)
 	{
 		rlgl.Begin(rlgl.TRIANGLES)
 		rlgl.End()
@@ -407,6 +410,8 @@ get_convex :: proc(assetman: ^Asset_Manager, path: cstring) -> (result: Loaded_C
 
 					tetra_centroid := (tri[0] + tri[1] + tri[2] + center) * 0.25
 					center_of_mass += tetra_volume * tetra_centroid
+					center_of_mass_tris += 1.0 / 3.0 * (tri[0] + tri[1] + tri[2]) * tri_area
+					total_area_tris += tri_area
 
 					tri_idx += 1
 				}
@@ -418,8 +423,13 @@ get_convex :: proc(assetman: ^Asset_Manager, path: cstring) -> (result: Loaded_C
 
 	assert(total_volume > 0, "degenerate convex hull")
 	center_of_mass /= total_volume
+	center_of_mass_tris /= total_area_tris
 
-	return {mesh = mesh, center_of_mass = center_of_mass}
+	return {
+		mesh = mesh,
+		center_of_mass = center_of_mass,
+		center_of_mass_tris = center_of_mass_tris,
+	}
 }
 
 debug_draw_tetrahedron_wires :: proc(tri: [3]rl.Vector3, p: rl.Vector3, color: rl.Color) {
diff --git a/game/game.odin b/game/game.odin
index ba9ab70..a3cafc5 100644
--- a/game/game.odin
+++ b/game/game.odin
@@ -555,8 +555,9 @@ draw :: proc() {
 		car_convex := assets.get_convex(&g_mem.assetman, "assets/car_convex.obj")
 
 		halfedge.debug_draw_mesh_wires(car_convex.mesh, rl.RED)
-		rl.DrawSphereWires(car_convex.mesh.center, 0.5, 8, 8, rl.BLUE)
+		rl.DrawSphereWires(car_convex.mesh.center, 0.0, 8, 8, rl.BLUE)
 		rl.DrawSphereWires(car_convex.center_of_mass, 0.5, 8, 8, rl.RED)
+		rl.DrawSphereWires(car_convex.center_of_mass_tris, 0.5, 8, 8, rl.GREEN)
 
 		box1_convex := collision.box_to_convex(box1, context.temp_allocator)
 		box2_convex := collision.box_to_convex(box2, context.temp_allocator)
diff --git a/game/physics/scene.odin b/game/physics/scene.odin
index 07f3991..f9e6db7 100644
--- a/game/physics/scene.odin
+++ b/game/physics/scene.odin
@@ -47,6 +47,8 @@ Shape_Box :: struct {
 	size: rl.Vector3,
 }
 
+Shape_Convex :: struct {}
+
 Collision_Shape :: union {
 	Shape_Sphere,
 	Shape_Box,