From d370265c833679c446498c3012bc87537b9b2a20 Mon Sep 17 00:00:00 2001
From: cinnaboot <cinnaboot@protonmail.com>
Date: Sat, 9 Apr 2022 13:44:50 -0400
Subject: [PATCH] add 'GameState' struct, and use 'user_data' in callbacks

---
 src/main.cpp | 65 ++++++++++++++++++++++++++++++----------------------
 1 file changed, 38 insertions(+), 27 deletions(-)

diff --git a/src/main.cpp b/src/main.cpp
index 3cb83da..5550c1f 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -13,15 +13,20 @@
 #include "orbits.h"
 
 
-static bool g_running = false;
-static system_2body g_sys = {0};
-static MemoryArena* g_arena = nullptr;
-
 const double SCALING = 0.001;
 const vec4 g_light_direction = vec4(-2, 1, 3, 1);
 const vec4 g_light_color = vec4(0.5, 0.5, 0.5, 1);
 const uvec4 g_light_intensities = uvec4(1, 0, 0, 0);
 
+struct GameState
+{
+	bool running;
+	MemoryArena* arena;
+
+	system_2body system;	// FIXME: we're going to need more than 1 system...
+	Entity* satellite_entity;
+};
+
 
 void
 initCamera(RenderState* rs, vec3 cam_pos, vec3 cam_focus, vec3 cam_up)
@@ -51,15 +56,15 @@ initLights(RenderState* rs)
 
 Entity*
 initEllipseEntity(RenderState* rs,
-	const ellipse_parameters& ep,
+	system_2body* system,
 	u32 num_vertices)
 {
-	g_sys.e3d = ellipseInit3D(g_sys.ep, num_vertices);
+	system->e3d = ellipseInit3D(system->ep, num_vertices);
 	Mesh* m = meshInit(rs->rg_arena, num_vertices, num_vertices, false, true);
 	vec3 vertex_color = vec3(255, 0, 255);
 
-	for (uint i = 0; i < g_sys.e3d.vert_count; i++) {
-		m->vertices[i] = g_sys.e3d.vertices[i];
+	for (uint i = 0; i < system->e3d.vert_count; i++) {
+		m->vertices[i] = system->e3d.vertices[i];
 		m->colors[i] = vertex_color;
 		m->indices[i] = i;
 	}
@@ -130,7 +135,7 @@ initSatelliteEntity(RenderState* rs)
 }
 
 void
-loadScene(RenderState* rs)
+loadScene(GameState* gs, RenderState* rs)
 {
 	initCamera(rs, vec3(0, -75 / SCALING, 0), vec3(0, 0, 0), vec3(0,0,1));
 	initLights(rs);
@@ -139,25 +144,25 @@ loadScene(RenderState* rs)
 	double e = 0.7411;		// NOTE: eccentricity
 	double mu = 398601.68;	// NOTE: gravitational parameter
 	double r = 6378;		// NOTE: body radius in km
-	g_sys = systemInit(gravBodyInit(mu, r), orbitInit(a, e));
-	g_running = true;
+	gs->system = systemInit(gravBodyInit(mu, r), orbitInit(a, e));
+	gs->running = true;
 
 	// TODO: streamline the boilerplate in init_X_Entity functions
-	g_arena = arenaInit(16);
 	ShaderProgram* shader = getShaderByName("colored_vertices", rs->gl_ctx);
 	initRenderGroup(
 		getFreeRenderGroup(rs), rs->rg_arena, shader, 256, "manual mesh group");
 
-	Entity* ellipse_entity = initEllipseEntity(rs, g_sys.ep, 256);
+	//Entity* ellipse_entity = initEllipseEntity(rs, g_sys.ep, 256);
+	Entity* ellipse_entity = initEllipseEntity(rs, &gs->system, 256);
 	setEntityPosition(ellipse_entity, vec3(0, 0, 0));
 	rotateEntity(ellipse_entity, vec3(1, 0, 0), (float) M_PI / 2);
 
 	initPlanetEntity(rs, r);
 
-	Entity* satellite_entity = initSatelliteEntity(rs);
-	scaleEntity(satellite_entity, 1 / SCALING);
-	rotateEntity(satellite_entity, vec3(1, 0, 0), (float) M_PI / 2);
-	setEntityPosition(satellite_entity, g_sys.e3d.vertices[0]);
+	gs->satellite_entity = initSatelliteEntity(rs);
+	scaleEntity(gs->satellite_entity, 1 / SCALING);
+	rotateEntity(gs->satellite_entity, vec3(1, 0, 0), (float) M_PI / 2);
+	setEntityPosition(gs->satellite_entity, gs->system.e3d.vertices[0]);
 }
 
 void
@@ -195,7 +200,7 @@ updateOrbit(system_2body sys, Entity& ellipse_entity)
 }
 
 void
-preFrameCallback(RenderState* rs)
+preFrameCallback(RenderState* rs, void* user_data = nullptr)
 {
 	static InputState is = {};
 	SDL_Event e;
@@ -211,14 +216,18 @@ preFrameCallback(RenderState* rs)
 }
 
 void
-postFrameCallback(RenderState* rs)
+postFrameCallback(RenderState* rs, void* user_data = nullptr)
 {
-	static Entity* satellite = nullptr;
-	gooDraw(rs->handles.window, g_sys, g_running);
-
-	if (g_running) {
-		updateSatelliteModel(g_sys, g_sys.sat);
-		g_sys.ep = ellipseInitAE(g_sys.ep.a, g_sys.ep.e);
+	assert(user_data != nullptr);
+	GameState* gs = (GameState*) user_data;
+	gooDraw(rs->handles.window, gs->system, gs->running);
+
+	if (gs->running) {
+		updateSatelliteModel(gs->system, gs->system.sat);
+		gs->system.ep = ellipseInitAE(gs->system.ep.a, gs->system.ep.e);
+		updateSatelliteEntity(gs->satellite_entity, gs->system.sat);
+		//updateOrbit(gs->system, ellipse_entity);
+	}
 
 		if (satellite == nullptr) {
 			RenderGroup* rg = getRenderGroupByName(rs, "manual mesh group");
@@ -248,8 +257,10 @@ main()
 		return 1;
 	}
 
-	loadScene(rs);
-	doRenderLoop(rs, 60, preFrameCallback, postFrameCallback);
+	GameState gs = {0};
+	gs.arena =  arenaInit(16);
+	loadScene(&gs, rs);
+	doRenderLoop(rs, 60, preFrameCallback, postFrameCallback, &gs);
 	gooFree();
 	freeRenderState(rs);