gravitation, no collisions

main.c

@@ -1,17 +1,25 @@
 #include <stddef.h>
 #include <raylib.h>
+#include <raymath.h>
 #include <stdio.h>
 #include "objects.h"
 
+
 struct global {
   const int scwidth, scheight;
   int fps;
   object *objs[128];
   size_t obj_count;
-  double terminal_yv;
+  double terminal_v;
 };
 
-struct global gl = {1600, 900, 60, {}, 0, -20};
+struct global gl = {1600, 900, 144, {}, 0, 15};
+
+float min(float a, float b)
+{return a>b?b:a;}
+
+float max(float a, float b)
+{return a>b?a:b;}
 
 void addobj(object *obj)
 {
@@ -27,23 +35,72 @@ void drawobjs()
   }
 }
 
+Vector3 gravitation_force(object *obj1, object *obj2)
+{
+	const double GRAVITY_FACTOR = 1;
+	Vector3 force;
+	double dist, mass, total_g;
+	mass = obj1->mass * obj2->mass;
+	force = Vector3Subtract(obj2->pos, obj1->pos);
+
+	dist = Vector3Length(force);
+	force = Vector3Normalize(force);
+
+	dist = max(dist, obj1->r+obj2->r);
+
+	total_g = GRAVITY_FACTOR * mass / (dist * dist);
+	force = Vector3Scale(force, total_g);
+
+	return force;
+}
+
+void integrate_g(object *obj1, object *obj2, Vector3 force)
+{
+	Vector3 acc;
+	double f, a;
+
+	f = Vector3Length(force);
+	//acc = Vector3Scale(Vector3Subtract(obj1->pos, obj2->pos), f);
+	acc = force;
+
+	a = f / obj1->mass;
+	acc = Vector3Scale(Vector3Normalize(acc), a*GetFrameTime());
+	obj1->vel = Vector3Add(obj1->vel, acc);
+
+	a = f / obj2->mass;
+	acc = Vector3Scale(Vector3Normalize(acc), a*GetFrameTime());
+	obj2->vel = Vector3Add(obj2->vel, acc);
+}
+
 void updateobjs()
 {
   for (int i = 0; i < gl.obj_count; i++)
   {
     object *obj = gl.objs[i];
-    obj->vel.y -= 9.81 * GetFrameTime();
-    if (obj->vel.y < gl.terminal_yv)
-    {
-      obj->vel.y = gl.terminal_yv;
-    }
+    obj->vel.y -= 0 * GetFrameTime();
+    //if (obj->vel.y < gl.terminal_yv)
     if (obj->pos.y < obj->r) {
       obj->pos.y = obj->r;
       obj->vel.y *= -obj->restitution;
     }
-    obj->pos.x += obj->vel.x * GetFrameTime();
-    obj->pos.y += obj->vel.y * GetFrameTime();
-    obj->pos.z += obj->vel.z * GetFrameTime();
+		for (int j = 0; j < gl.obj_count; j++)
+		{
+			if (i==j) continue;
+			object *obj2 = gl.objs[j];
+			integrate_g(obj, obj2, gravitation_force(obj, obj2));
+			//float min_dist_delta = Vector3Distance(obj->pos, obj2->pos) - (obj->r+obj2->r);
+			//if (min_dist_delta < 0)
+			//{
+			//	Vector3SubtractValue(obj->pos, min_dist_delta);
+			//}
+		}
+		float ratio_speed_to_terminal = Vector3Length(obj->vel)/gl.terminal_v;
+		if (Vector3Length(obj->vel) > gl.terminal_v)
+    {
+			obj->vel = Vector3Scale(obj->vel, 1.0f/ratio_speed_to_terminal);
+		}
+		DrawLine3D(obj->pos, Vector3Add(obj->pos, obj->vel), GREEN);
+		obj->pos = Vector3Add(obj->pos, Vector3Scale(obj->vel, GetFrameTime()));
   } 
 }
 
@@ -56,23 +113,17 @@ void freeobjs()
   } 
 }
 
-void applyforce()
-{
-  for (int i = 0; i < gl.obj_count; i++)
-  {
-    object *obj = gl.objs[i];
-    obj->vel.x += 1;
-  }
-}
-
 int main(void) {
 
   InitWindow(gl.scwidth, gl.scheight, "raylib engine");
 
   SetTargetFPS(gl.fps);
-  addobj(newobj((Vector3){0, 30, 0}, 2, RED, 0.5));
-  addobj(newobj((Vector3){5, 2, 0}, 1, BLUE, 1));
+  addobj(newobj((Vector3){0, 20, 0}, 3, RED, 1, 50000));
+  addobj(newobj((Vector3){4, 20, 0}, 1, BLUE, 1, 1000));
+  addobj(newobj((Vector3){-6, 18, 0}, 2, GREEN, 1, 2000));
+	gl.objs[1]->vel = (Vector3){0, 0, 2};
   Camera3D camera = {{0, 20, -30}, {0, 0, 0}, {0, 1, 0}, 45, CAMERA_PERSPECTIVE};
+	DisableCursor();
 
   while(!WindowShouldClose())
   {
@@ -85,11 +136,6 @@ int main(void) {
       DrawPlane((Vector3){0, 0, 0}, (Vector2){100, 100}, GRAY);
       updateobjs();
       drawobjs();
-
-      if (IsKeyPressed(KEY_L)) {
-        applyforce();
-      }
-
       EndMode3D();
     }
     EndDrawing();

objects.h

@@ -5,12 +5,13 @@
 typedef struct {
   Vector3 pos;
   Vector3 vel;
-  float r;
+  double r;
   Color color;
-  float restitution;
+  double restitution;
+	double mass;
 } object;
 
-object *newobj(Vector3 pos, float r, Color c, float rest)
+object *newobj(Vector3 pos, double r, Color c, double rest, double m)
 {
   object *obj = (object*)malloc(sizeof(object));
   obj->r = r;
@@ -18,5 +19,6 @@ object *newobj(Vector3 pos, float r, Color c, float rest)
   obj->color = c;
   obj->vel = (Vector3){0, 0, 0};
   obj->restitution = rest;
+	obj->mass = m;
   return obj;
 }