fleshed out the object model a bit.

made a rocket that blasts off!

sim/sim.c

@@ -3,67 +3,126 @@
 #include <stdlib.h>
 #include <OpenGL/gl.h>
 
-struct SimContext
-{
-  double t;
+typedef double SimUnit;
+#define SimUnitZero 0
+
+struct Sim3Vector {
+  SimUnit x, y, z;
 };
-typedef struct SimContext *SimContext;
+typedef struct Sim3Vector Sim3Vector;
 
-SimContextRef SimContextCreate() {
-  SimContext result = (SimContext)malloc(sizeof(SimContext));
-  result->t = 0.0;
-  return (SimContext)result;
+#define Sim3VectorZero ((Sim3Vector){ .x = SimUnitZero, .y = SimUnitZero, .z = SimUnitZero })
+#define Sim3VectorMake(X, Y, Z) ((Sim3Vector){ .x = (X), .y = (Y), .z = (Z) })
+#define Sim3VectorAdd(A, B) ((Sim3Vector){ .x = (A).x + (B).x, .y = (A).y + (B).y, .z = (A).z + (B).z })
+#define Sim3VectorScale(K, V) ((Sim3Vector){ .x = (K) * (V).x, .y = (K) * (V).y, .z = (K) * (V).z })
+
+struct SimThruster {
+  Sim3Vector thrust;
+};
+typedef struct SimThruster *SimThrusterRef;
+
+SimThrusterRef SimThrusterCreate() {
+  SimThrusterRef result = (SimThrusterRef)malloc(sizeof(struct SimThruster));
+  result->thrust = Sim3VectorZero;
+  return result;
 }
 
-void SimContextDestroy(SimContextRef c) {
-  free(c);
+void SimThrusterDestroy(SimThrusterRef ref) {
+  free(ref);
 }
 
-void SimContextUpdate(SimContextRef c, double t) {
-  SimContext ctx = c;
-  ctx->t += t * .0001;
+struct SimVehicle {
+  Sim3Vector position;
+  Sim3Vector velocity;
+
+  Sim3Vector angle;
+  Sim3Vector angularVelocity;
+
+  SimUnit mass;
+
+  SimThrusterRef thruster;
+};
+typedef struct SimVehicle *SimVehicleRef;
+
+SimVehicleRef SimVehicleCreate() {
+  SimVehicleRef result = (SimVehicleRef)malloc(sizeof(struct SimVehicle));
+
+  result->position = Sim3VectorZero;
+  result->velocity = Sim3VectorZero;
+
+  result->angle = Sim3VectorZero;
+  result->angularVelocity = Sim3VectorZero;
+
+  result->mass = SimUnitZero;
+  result->thruster = SimThrusterCreate();
+  return result;
 }
 
-void SimContextDraw(SimContextRef c, double t) {
-  SimContext ctx = c;
-
-  glRotated(ctx->t, 0,0,1);
+void SimVehicleDestroy(SimVehicleRef ref) {
+  SimThrusterDestroy(ref->thruster);
+  free(ref);
+}
 
-  glClearColor(0,0,0,0);
-  glClear(GL_COLOR_BUFFER_BIT);
+void SimVehicleUpdate(SimVehicleRef ref, SimUnit t) {
+  ref->position = Sim3VectorAdd(ref->position, Sim3VectorScale(1/t, ref->velocity));
+  ref->velocity = Sim3VectorAdd(ref->velocity, Sim3VectorScale(1/t, ref->thruster->thrust));
+}
+
+void SimVehicleDraw(SimVehicleRef ref, SimUnit t) {
+  glPushMatrix();
+
+  glTranslated(ref->position.x, ref->position.y, ref->position.z);
 
   glColor3f(1.0f, 0.85f, 0.35f);
   glBegin(GL_TRIANGLES);
   {
-    glVertex3f(  0.0,  0.6, 0.0);
-    glVertex3f( -0.2, -0.3, 0.0);
-    glVertex3f(  0.2, -0.3 ,0.0);
+    glVertex3f(  0.0,  0.5, 0.0);
+    glVertex3f( -0.2, -0.5, 0.0);
+    glVertex3f(  0.2, -0.5 ,0.0);
   }
   glEnd(); 
-  glFlush();
+
+  glPopMatrix();
 }
 
+struct SimContext {
+  SimVehicleRef vehicle;
+};
+typedef struct SimContext *SimContext;
 
-    // const int TICKS_PER_SECOND = 25;
-    // const int SKIP_TICKS = 1000 / TICKS_PER_SECOND;
-    // const int MAX_FRAMESKIP = 5;
+SimContextRef SimContextCreate() {
+  SimContext result = (SimContext)malloc(sizeof(struct SimContext));
+  result->vehicle = SimVehicleCreate();
+  result->vehicle->thruster->thrust = Sim3VectorMake(0,0.00001,0);
+  return result;
+}
 
-    // DWORD next_game_tick = GetTickCount();
-    // int loops;
-    // float interpolation;
+void SimContextDestroy(SimContextRef ref) {
+  SimContext self = ref;
+  SimVehicleDestroy(self->vehicle);
+  free(ref);
+}
 
-    // bool game_is_running = true;
-    // while( game_is_running ) {
+void SimContextUpdate(SimContextRef c, double t) {
+  SimContext ctx = c;
 
-    //     loops = 0;
-    //     while( GetTickCount() > next_game_tick && loops < MAX_FRAMESKIP) {
-    //         update_game();
+  SimVehicleUpdate(ctx->vehicle, t);
+}
 
-    //         next_game_tick += SKIP_TICKS;
-    //         loops++;
-    //     }
+void SimContextDraw(SimContextRef c, double t) {
+  SimContext ctx = c;
+
+  glClearColor(0,0,0,0);
+  glClear(GL_COLOR_BUFFER_BIT);
+
+  glPushMatrix();
 
-    //     interpolation = float( GetTickCount() + SKIP_TICKS - next_game_tick )
-    //                     / float( SKIP_TICKS );
-    //     display_game( interpolation );
-    // }
+  glTranslatef(0,-1,0);
+  glScalef(.1,.1,.1);
+
+  SimVehicleDraw(ctx->vehicle, t);
+
+  glPopMatrix();
+
+  glFlush();
+}

sim/sim.h

@@ -1,5 +1,4 @@
 
-
 typedef void *SimContextRef;
 
 SimContextRef SimContextCreate();