update gitignore

.gitignore

@@ -5,8 +5,11 @@ CMakeSettings.json
 
 out/
 build/
+winbuild/
 xcode/
 cmake-build-*/
 
 Thumbs.db
 .DS_Store
+*.exe
+*.dll

CMakeLists.txt

@@ -15,6 +15,6 @@ target_compile_definitions(Lesson10 PRIVATE $<$<CXX_COMPILER_ID:MSVC>:_CRT_SECUR
 if (CMAKE_SYSTEM_NAME STREQUAL "Darwin")
 	get_property(SDL3_IMPORTED_LOCATION TARGET SDL3::SDL3 PROPERTY IMPORTED_LOCATION)
 	if (SDL3_IMPORTED_LOCATION MATCHES "^/Library/Frameworks/")
-		target_link_options(Lesson10 PRIVATE -Wl,-rpath,/Library/Frameworks)
+		set_property(TARGET Lesson10 PROPERTY BUILD_RPATH "/Library/Frameworks")
 	endif()
 endif()

Lesson10.c

@@ -1,54 +1,58 @@
 /*
- *      This Code Was Created By Lionel Brits & Jeff Molofee 2000
- *      A HUGE Thanks To Fredric Echols For Cleaning Up
- *      And Optimizing The Base Code, Making It More Flexible!
- *      If You've Found This Code Useful, Please Let Me Know.
- *      Visit My Site At nehe.gamedev.net
+ *  This code was created by Lionel Brits & Jeff Molofee 2000.
+ *  A HUGE thanks to Fredric Echols for cleaning up
+ *  and optimizing the base code, making it more flexible!
+ *  If you've found this code useful, please let me know.
+ *  Visit my site at https://nehe.gamedev.net
  */
 
-#include <math.h>              // Math Library Header File
-#include <stdio.h>             // Header File For Standard Input/Output
+#include <math.h>
+#include <stdio.h>
 #include <stdlib.h>
 #include <stdbool.h>
 #include <SDL3/SDL.h>
 #define SDL_MAIN_USE_CALLBACKS
 #include <SDL3/SDL_main.h>
-#include <SDL3/SDL_opengl.h>   // Header File For The OpenGL32 Library
+#include <SDL3/SDL_opengl.h>
 
-SDL_Window*   win = NULL;      // Holds Our Window Handle
-SDL_GLContext ctx = NULL;      // Permanent Rendering Context
+#define BTTN_YES 0
+#define BTTN_NO  1
 
-bool fullscreen = false;
-bool blend = false;            // Blending ON/OFF
-
-static const SDL_MessageBoxButtonData yesnobttns[2] =
+static int ShowYesNoMessageBox(SDL_Window *window, int defaultbttn, const char *title, const char *message)
 {
+	const SDL_MessageBoxButtonFlags defaultflags =
+		SDL_MESSAGEBOX_BUTTON_RETURNKEY_DEFAULT | SDL_MESSAGEBOX_BUTTON_ESCAPEKEY_DEFAULT;
+	const SDL_MessageBoxButtonData yesnobttns[2] =
 	{
-		/*flags    */ 0,
-		/*buttonid */ 0,
-		/*text     */ "Yes"
-	},
+		{ .flags = defaultbttn == BTTN_YES ? defaultflags : 0, .buttonID = BTTN_YES, .text = "Yes" },
+		{ .flags = defaultbttn == BTTN_NO  ? defaultflags : 0, .buttonID = BTTN_NO,  .text = "No"  }
+	};
+	const SDL_MessageBoxData msgbox =
 	{
-		/*flags    */ SDL_MESSAGEBOX_BUTTON_RETURNKEY_DEFAULT | SDL_MESSAGEBOX_BUTTON_ESCAPEKEY_DEFAULT,
-		/*buttonid */ 1,
-		/*text     */ "No"
-	}
-};
+		.flags       = SDL_MESSAGEBOX_INFORMATION,
+		.window      = window,
+		.title       = title,
+		.message     = message,
+		.numbuttons  = 2,
+		.buttons     = yesnobttns,
+		.colorScheme = NULL
+	};
+
+	int bttnid = defaultbttn;
+	SDL_ShowMessageBox(&msgbox, &bttnid);
+	return bttnid;
+}
 
 typedef struct tagCAMERA
 {
 	float heading;
 	float xpos, zpos;
-	float yrot;                   // Y Rotation
+	float yrot;
 	float walkbias, walkbiasangle;
 	float lookupdown;
-	float z;                      // Depth Into The Screen
+	float z;
 } CAMERA;
 
-CAMERA camera;
-unsigned filter;                  // Which Filter To Use
-GLuint texture[3] = { 0, 0, 0 };  // Storage For 3 Textures
-
 typedef struct tagVERTEX
 {
 	float x, y, z;
@@ -63,13 +67,24 @@ typedef struct tagTRIANGLE
 typedef struct tagSECTOR
 {
 	int numtriangles;
-	TRIANGLE* triangle;
+	TRIANGLE *triangle;
 } SECTOR;
 
-// Our Model Goes Here:
-SECTOR sector1 = { .numtriangles = 0, .triangle = NULL };
+typedef struct tagAPPSTATE
+{
+	SDL_Window   *win;
+	SDL_GLContext ctx;
 
-void readstr(FILE *f, char *string)
+	bool fullscreen, blend;
+
+	CAMERA camera;
+	unsigned filter;    // Filtered texture selection
+	GLuint texture[3];  // Filtered textures
+
+	SECTOR sector1;
+} APPSTATE;
+
+static void readstr(FILE *f, char *string)
 {
 	do
 	{
@@ -78,37 +93,37 @@ void readstr(FILE *f, char *string)
 	return;
 }
 
-void SetupWorld(void)
+static void SetupWorld(APPSTATE *state)
 {
 	float x, y, z, u, v;
 	int numtriangles;
 	FILE *filein;
 	char oneline[255];
-	filein = fopen("data/world.txt", "r");  // File To Load World Data From
+	filein = fopen("data/world.txt", "r");  // File to load world data from
 
 	readstr(filein, oneline);
 	sscanf(oneline, "NUMPOLLIES %d\n", &numtriangles);
 
-	sector1.triangle = malloc(sizeof(TRIANGLE) * numtriangles);
-	sector1.numtriangles = numtriangles;
+	state->sector1.triangle = malloc(sizeof(TRIANGLE) * numtriangles);
+	state->sector1.numtriangles = numtriangles;
 	for (int loop = 0; loop < numtriangles; loop++)
 	{
 		for (int vert = 0; vert < 3; vert++)
 		{
 			readstr(filein, oneline);
 			sscanf(oneline, "%f %f %f %f %f", &x, &y, &z, &u, &v);
-			sector1.triangle[loop].vertex[vert].x = x;
-			sector1.triangle[loop].vertex[vert].y = y;
-			sector1.triangle[loop].vertex[vert].z = z;
-			sector1.triangle[loop].vertex[vert].u = u;
-			sector1.triangle[loop].vertex[vert].v = v;
+			state->sector1.triangle[loop].vertex[vert].x = x;
+			state->sector1.triangle[loop].vertex[vert].y = y;
+			state->sector1.triangle[loop].vertex[vert].z = z;
+			state->sector1.triangle[loop].vertex[vert].u = u;
+			state->sector1.triangle[loop].vertex[vert].v = v;
 		}
 	}
 	fclose(filein);
 	return;
 }
 
-bool FlipSurface(SDL_Surface *surface)
+static bool FlipSurface(SDL_Surface *surface)
 {
 	if (!surface || SDL_LockSurface(surface) < 0)
 	{
@@ -138,17 +153,17 @@ bool FlipSurface(SDL_Surface *surface)
 	return true;
 }
 
-bool LoadGLTextures(void)              // Load bitmap as textures
+static bool LoadGLTextures(APPSTATE *state)
 {
-	SDL_Surface *TextureImage = NULL;  // Create Storage Space For The Texture
+	SDL_Surface *TextureImage = NULL;
 
-	// Load & flip the bitmap, check for errors
+	// Load & flip the bitmap
 	if (!(TextureImage = SDL_LoadBMP("Data/Mud.bmp")) || !FlipSurface(TextureImage))
 	{
 		return false;
 	}
 
-	glGenTextures(3, &texture[0]);     // Create three textures
+	glGenTextures(3, &state->texture[0]);                        // Create three textures
 	GLint params[3][3] =
 	{
 		[0] = { GL_NEAREST, GL_NEAREST, GL_FALSE },              // Nearest filtered
@@ -157,7 +172,7 @@ bool LoadGLTextures(void)              // Load bitmap as textures
 	};
 	for (int i = 0; i < 3; i++)
 	{
-		glBindTexture(GL_TEXTURE_2D, texture[i]);
+		glBindTexture(GL_TEXTURE_2D, state->texture[i]);
 		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, params[i][0]);
 		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, params[i][1]);
 		glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, params[i][2]);
@@ -166,7 +181,8 @@ bool LoadGLTextures(void)              // Load bitmap as textures
 			0, GL_BGR, GL_UNSIGNED_BYTE, TextureImage->pixels);
 	}
 
-	SDL_DestroySurface(TextureImage);  // Free the image structure
+	// Free temporary surface
+	SDL_DestroySurface(TextureImage);
 	return true;
 }
 
@@ -187,235 +203,220 @@ static void gluPerspective(GLdouble fovy, GLdouble aspect, GLdouble zNear, GLdou
 	glLoadMatrixd(mtx);
 }
 
-void ReSizeGLScene(int width, int height)                // Resize And Initialize The GL Window
+/*  Set viewport size and setup matrices         *
+ *  width   - Width of the OpenGL framebuffer    *
+ *  height  - Height of the OpenGL framebuffer   */
+static void ReSizeGLScene(int width, int height)
 {
-	if (height == 0)                                     // Prevent A Divide By Zero By
+	if (height == 0)                              // Prevent division-by-zero by ensuring height is non-zero
 	{
-		height = 1;                                      // Making Height Equal One
+		height = 1;
 	}
 
-	glViewport(0, 0, width, height);                     // Reset The Current Viewport
+	glViewport(0, 0, width, height);              // Reset the current viewport
 
-	glMatrixMode(GL_PROJECTION);                         // Select The Projection Matrix
-	glLoadIdentity();                                    // Reset The Projection Matrix
+	glMatrixMode(GL_PROJECTION);                  // Select & reset the projection matrix
+	glLoadIdentity();
 
-	// Calculate The Aspect Ratio Of The Window
-	gluPerspective(45.0f, (float)width / (float)height, 0.1f, 100.0f);
+	float aspect = (float)width / (float)height;  // Calculate aspect ratio
+	gluPerspective(45.0f, aspect, 0.1f, 100.0f);  // Setup perspective matrix
 
-	glMatrixMode(GL_MODELVIEW);                          // Select The Modelview Matrix
-	glLoadIdentity();                                    // Reset The Modelview Matrix
+	glMatrixMode(GL_MODELVIEW);                   // Select & reset the modelview matrix
+	glLoadIdentity();
 }
 
-bool InitGL(void)                                        // All Setup For OpenGL Goes Here
+static bool InitGL(APPSTATE *state)
 {
-	if (!LoadGLTextures())                               // Jump To Texture Loading Routine
+	if (!LoadGLTextures(state))                         // Load textures
 	{
 		return false;
 	}
 
-	glEnable(GL_TEXTURE_2D);                             // Enable Texture Mapping
-	glBlendFunc(GL_SRC_ALPHA, GL_ONE);                   // Set The Blending Function For Translucency
-	glClearColor(0.0f, 0.0f, 0.0f, 0.0f);                // This Will Clear The Background Color To Black
-	glClearDepth(1.0);                                   // Enables Clearing Of The Depth Buffer
-	glDepthFunc(GL_LESS);                                // The Type Of Depth Test To Do
-	glEnable(GL_DEPTH_TEST);                             // Enables Depth Testing
-	glShadeModel(GL_SMOOTH);                             // Enables Smooth Color Shading
-	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);   // Really Nice Perspective Calculations
+	glEnable(GL_TEXTURE_2D);                            // Enable texture mapping
+	glBlendFunc(GL_SRC_ALPHA, GL_ONE);                  // Set the blending function for translucency
+	glClearColor(0.0f, 0.0f, 0.0f, 0.0f);               // Set the background clear color to black
+	glClearDepth(1.0);                                  // Ensure depth buffer clears to furthest value
+	glDepthFunc(GL_LESS);                               // Pass if pixel depth value tests less than the depth buffer value
+	glEnable(GL_DEPTH_TEST);                            // Enable depth testing
+	glShadeModel(GL_SMOOTH);                            // Enable Smooth color shading
+	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);  // Request the implementation to use perspective correct interpolation
 
-	SetupWorld();
+	SetupWorld(state);
 
-	return true;                                         // Initialization Went OK
+	return true;
 }
 
-void DrawGLScene(void)                                   // Here's Where We Do All The Drawing
+static void DrawGLScene(APPSTATE *state)
 {
-	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);  // Clear The Screen And The Depth Buffer
-	glLoadIdentity();                                    // Reset The View
+	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);  // Clear the color and depth buffers
+	glLoadIdentity();                                    // Reset modelview
 
 	GLfloat x_m, y_m, z_m, u_m, v_m;
-	GLfloat xtrans = -camera.xpos;
-	GLfloat ztrans = -camera.zpos;
-	GLfloat ytrans = -camera.walkbias - 0.25f;
-	GLfloat sceneroty = 360.0f - camera.yrot;
+	GLfloat xtrans = -state->camera.xpos;
+	GLfloat ztrans = -state->camera.zpos;
+	GLfloat ytrans = -state->camera.walkbias - 0.25f;
+	GLfloat sceneroty = 360.0f - state->camera.yrot;
 
 	int numtriangles;
 
-	glRotatef(camera.lookupdown, 1.0f, 0.0f, 0.0f);
+	glRotatef(state->camera.lookupdown, 1.0f, 0.0f, 0.0f);
 	glRotatef(sceneroty, 0.0f, 1.0f, 0.0f);
 
 	glTranslatef(xtrans, ytrans, ztrans);
-	glBindTexture(GL_TEXTURE_2D, texture[filter]);
+	glBindTexture(GL_TEXTURE_2D, state->texture[state->filter]);
 
-	numtriangles = sector1.numtriangles;
+	numtriangles = state->sector1.numtriangles;
 
-	// Process Each Triangle
 	for (int loop_m = 0; loop_m < numtriangles; loop_m++)
 	{
 		glBegin(GL_TRIANGLES);
 			glNormal3f(0.0f, 0.0f, 1.0f);
-			x_m = sector1.triangle[loop_m].vertex[0].x;
-			y_m = sector1.triangle[loop_m].vertex[0].y;
-			z_m = sector1.triangle[loop_m].vertex[0].z;
-			u_m = sector1.triangle[loop_m].vertex[0].u;
-			v_m = sector1.triangle[loop_m].vertex[0].v;
+			x_m = state->sector1.triangle[loop_m].vertex[0].x;
+			y_m = state->sector1.triangle[loop_m].vertex[0].y;
+			z_m = state->sector1.triangle[loop_m].vertex[0].z;
+			u_m = state->sector1.triangle[loop_m].vertex[0].u;
+			v_m = state->sector1.triangle[loop_m].vertex[0].v;
 			glTexCoord2f(u_m, v_m); glVertex3f(x_m, y_m, z_m);
 
-			x_m = sector1.triangle[loop_m].vertex[1].x;
-			y_m = sector1.triangle[loop_m].vertex[1].y;
-			z_m = sector1.triangle[loop_m].vertex[1].z;
-			u_m = sector1.triangle[loop_m].vertex[1].u;
-			v_m = sector1.triangle[loop_m].vertex[1].v;
+			x_m = state->sector1.triangle[loop_m].vertex[1].x;
+			y_m = state->sector1.triangle[loop_m].vertex[1].y;
+			z_m = state->sector1.triangle[loop_m].vertex[1].z;
+			u_m = state->sector1.triangle[loop_m].vertex[1].u;
+			v_m = state->sector1.triangle[loop_m].vertex[1].v;
 			glTexCoord2f(u_m, v_m); glVertex3f(x_m, y_m, z_m);
 
-			x_m = sector1.triangle[loop_m].vertex[2].x;
-			y_m = sector1.triangle[loop_m].vertex[2].y;
-			z_m = sector1.triangle[loop_m].vertex[2].z;
-			u_m = sector1.triangle[loop_m].vertex[2].u;
-			v_m = sector1.triangle[loop_m].vertex[2].v;
+			x_m = state->sector1.triangle[loop_m].vertex[2].x;
+			y_m = state->sector1.triangle[loop_m].vertex[2].y;
+			z_m = state->sector1.triangle[loop_m].vertex[2].z;
+			u_m = state->sector1.triangle[loop_m].vertex[2].u;
+			v_m = state->sector1.triangle[loop_m].vertex[2].v;
 			glTexCoord2f(u_m, v_m); glVertex3f(x_m, y_m, z_m);
 		glEnd();
 	}
 }
 
-void KillGLWindow(void)                           // Properly Kill The Window
+static void KillGLWindow(APPSTATE *state)
 {
-	if (fullscreen)                               // Are We In Fullscreen Mode?
+	// Restore windowed state & cursor visibility
+	if (state->fullscreen)
 	{
-		SDL_SetWindowFullscreen(win, SDL_FALSE);  // If So Switch Back To The Desktop
-		SDL_ShowCursor();                         // Show Mouse Pointer
+		SDL_SetWindowFullscreen(state->win, SDL_FALSE);
+		SDL_ShowCursor();
 	}
 
-	if (ctx)                                      // Do We Have A Rendering Context?
+	// Release and delete rendering context
+	if (state->ctx)
 	{
-		if (SDL_GL_MakeCurrent(win, NULL))        // Are We Able To Release The DC And RC Contexts?
+		if (SDL_GL_MakeCurrent(state->win, NULL))
 		{
 			SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_INFORMATION, "SHUTDOWN ERROR", "Release Of RC Failed.", NULL);
 		}
 
-		SDL_GL_DeleteContext(ctx);                // Delete The RC
-		ctx = NULL;                               // Set RC To NULL
+		SDL_GL_DeleteContext(state->ctx);
+		state->ctx = NULL;
 	}
 
-	SDL_DestroyWindow(win);                       // Destroy The Window
-	win = NULL;                                   // Set hWnd To NULL
+	SDL_DestroyWindow(state->win);
+	state->win = NULL;
 }
 
 
-/*  This Code Creates Our OpenGL Window.  Parameters Are:                   *
- *  title           - Title To Appear At The Top Of The Window              *
- *  width           - Width Of The GL Window Or Fullscreen Mode             *
- *  height          - Height Of The GL Window Or Fullscreen Mode            *
- *  bits            - Number Of Bits To Use For Color (8/16/24/32)          *
- *  fullscreenflag  - Use Fullscreen Mode (TRUE) Or Windowed Mode (FALSE)   */
-
-
-bool CreateGLWindow(char *title, int width, int height, int bits, bool fullscreenflag)
+/*  This code creates our OpenGL window, parameters are:                    *
+ *  title           - Title to appear at the top of the window              *
+ *  width           - Width of the OpenGL window or fullscreen mode         *
+ *  height          - Height of the OpenGL window or fullscreen mode        *
+ *  bits            - Number of bits to use for color (8/16/24/32)          *
+ *  fullscreenflag  - Use fullscreen mode (true) Or windowed mode (false)   */
+static bool CreateGLWindow(APPSTATE *state, char *title, int width, int height, int bits, bool fullscreenflag)
 {
-	SDL_Rect WindowRect;                                  // Grabs Rectangle Upper Left / Lower Right Values
-	WindowRect.x = 0;                                     // Set Left Value To 0
-	WindowRect.w = width;                                 // Set Right Value To Requested Width
-	WindowRect.y = 0;                                     // Set Top Value To 0
-	WindowRect.h = height;                                // Set Bottom Value To Requested Height
+	state->fullscreen = fullscreenflag;
 
-	fullscreen = fullscreenflag;                          // Set The Global Fullscreen Flag
-
-	// Create The Window
-	if (!(win = SDL_CreateWindow(title,
-		WindowRect.w,                                     // Window Width
-		WindowRect.h,                                     // Window Height
+	if (!(state->win = SDL_CreateWindow(title, width, height,
 		SDL_WINDOW_HIDDEN | SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE | SDL_WINDOW_HIGH_PIXEL_DENSITY)))
 	{
 		SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "ERROR", "Window Creation Error.", NULL);
-		return false;                                     // Return FALSE
+		return false;
 	}
 
-	if (fullscreen)                                       // Attempt Fullscreen Mode?
+	// Try entering fullscreen mode if requested
+	if (fullscreenflag)
 	{
-		if (SDL_SetWindowFullscreen(win, SDL_TRUE) < 0)   // Try To Set Selected Mode And Get Results.
+		if (SDL_SetWindowFullscreen(state->win, SDL_TRUE) < 0)
 		{
-			// If The Mode Fails, Offer Two Options.  Quit Or Use Windowed Mode.
-			const SDL_MessageBoxData msgbox =
+			// If mode switching fails, ask the user to quit or use to windowed mode
+			int bttnid = ShowYesNoMessageBox(state->win, BTTN_YES, "NeHe GL",
+				"The Requested Fullscreen Mode Is Not Supported By\nYour Video Card. Use Windowed Mode Instead?");
+			if (bttnid == BTTN_NO)
 			{
-				SDL_MESSAGEBOX_INFORMATION,
-				win,
-				"NeHe GL",
-				"The Requested Fullscreen Mode Is Not Supported By\nYour Video Card. Use Windowed Mode Instead?",
-				2,
-				yesnobttns,
-				NULL
-			};
-			int bttnid = 0;
-			SDL_ShowMessageBox(&msgbox, &bttnid);
-			if (bttnid == 1)
-			{
-				// Pop Up A Message Box Letting User Know The Program Is Closing.
+				// User chose to quit
 				SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_WARNING, "ERROR", "Program Will Now Close.", NULL);
-				return false;                             // Return FALSE
+				return false;
 			}
-			fullscreen = false;
+			state->fullscreen = false;
 		}
 	}
 
 	SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_COMPATIBILITY);
 	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 1);
 	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 4);
-	SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);        // Must Support Double Buffering
-	SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 0);            // Color Bits Ignored
+	SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);           // Double buffered framebuffer
+	SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 0);               // Color bits ignored
 	SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 0);
 	SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 0);
-	SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE, 0);          // No Alpha Buffer
-	SDL_GL_SetAttribute(SDL_GL_ACCUM_ALPHA_SIZE, 0);    // No Accumulation Buffer
-	SDL_GL_SetAttribute(SDL_GL_ACCUM_RED_SIZE, 0);      // Accumulation Bits Ignored
+	SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE, 0);             // No alpha buffer
+	SDL_GL_SetAttribute(SDL_GL_ACCUM_ALPHA_SIZE, 0);       // No accumulation buffer
+	SDL_GL_SetAttribute(SDL_GL_ACCUM_RED_SIZE, 0);         // Accumulation bits ignored
 	SDL_GL_SetAttribute(SDL_GL_ACCUM_GREEN_SIZE, 0);
 	SDL_GL_SetAttribute(SDL_GL_ACCUM_BLUE_SIZE, 0);
-	SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 16);         // 16Bit Z-Buffer (Depth Buffer)
-	SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 0);        // No Stencil Buffer
+	SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 16);            // 16-bit Z-buffer (depth buffer)
+	SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 0);           // No stencil buffer
 
 
-	if (!(ctx = SDL_GL_CreateContext(win)))             // Are We Able To Get A Rendering Context?
+	if (!(state->ctx = SDL_GL_CreateContext(state->win)))  // Create rendering context
 	{
 		SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "ERROR", "Can't Create A GL Rendering Context.", NULL);
-		return false;                                   // Return FALSE
+		return false;
 	}
 
-	if (SDL_GL_MakeCurrent(win, ctx))                   // Try To Activate The Rendering Context
+	if (SDL_GL_MakeCurrent(state->win, state->ctx))        // Activate the rendering context
 	{
 		SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "ERROR", "Can't Activate The GL Rendering Context.", NULL);
-		return false;                                   // Return FALSE
+		return false;
 	}
 
-	SDL_ShowWindow(win);
-	SDL_GL_SetSwapInterval(1);
-	ReSizeGLScene(width, height);                       // Set Up Our Perspective GL Screen
+	SDL_ShowWindow(state->win);
+	SDL_GL_SetSwapInterval(1);                             // Enable VSync
+	ReSizeGLScene(width, height);                          // Set up our viewport and perspective
 
-	if (!InitGL())                                      // Initialize Our Newly Created GL Window
+	if (!InitGL(state))                                    // Initialize the scene
 	{
 		SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "ERROR", "Initialization Failed.", NULL);
-		return false;                                   // Return FALSE
+		return false;
 	}
 
-	return true;                                        // Success
+	return true;
 }
 
-int SDL_AppEvent(const SDL_Event *event)
+int SDL_AppEvent(void *appstate, const SDL_Event *event)
 {
+	APPSTATE *state = (APPSTATE *)appstate;
 	switch (event->type)
 	{
 	case SDL_EVENT_QUIT:                                          // Have we received a quit event?
-		return 1;                                                 // Exit with success status
+		return SDL_APP_SUCCESS;
 
 	case SDL_EVENT_KEY_DOWN:
-		if (event->key.keysym.sym == SDLK_ESCAPE)                 // Quit on Escape
+		if (event->key.keysym.sym == SDLK_ESCAPE)                 // Quit on escape key
 		{
-			return 1;                                             // Exit with success status
+			return SDL_APP_SUCCESS;
 		}
 		if (!event->key.repeat)                                   // Was a key just pressed?
 		{
 			switch (event->key.keysym.sym)
 			{
 			case SDLK_b:                                          // B = Toggle blending
-				blend = !blend;
-				if (!blend)
+				state->blend = !state->blend;
+				if (!state->blend)
 				{
 					glDisable(GL_BLEND);
 					glEnable(GL_DEPTH_TEST);
@@ -425,164 +426,182 @@ int SDL_AppEvent(const SDL_Event *event)
 					glEnable(GL_BLEND);
 					glDisable(GL_DEPTH_TEST);
 				}
-				return 0;
+				break;
 
 			case SDLK_f:                                          // F = Cycle texture filtering
-				filter += 1;
-				if (filter > 2)
+				state->filter += 1;
+				if (state->filter > 2)
 				{
-					filter = 0;
+					state->filter = 0;
 				}
-				return 0;
+				break;
 
-			case SDLK_F1:                                         // F1 = Toggle Fullscreen / Windowed Mode
-				SDL_SetWindowFullscreen(win, !fullscreen);
-				return 0;
+			case SDLK_F1:                                         // F1 = Toggle fullscreen / windowed mode
+				SDL_SetWindowFullscreen(state->win, !state->fullscreen);
+				break;
 
-			default: return 0;
+			default: break;
 			}
 		}
-		return 0;
+		break;
 
 	case SDL_EVENT_WINDOW_PIXEL_SIZE_CHANGED:                     // Deal with window resizes
 		ReSizeGLScene(event->window.data1, event->window.data2);  // data1=Backbuffer Width, data2=Backbuffer Height
-		return 0;
+		break;
 
 		case SDL_EVENT_WINDOW_ENTER_FULLSCREEN:
-			fullscreen = true;
-			return 0;
+			state->fullscreen = true;
+			break;
 
 		case SDL_EVENT_WINDOW_LEAVE_FULLSCREEN:
-			fullscreen = false;
-			return 0;
+			state->fullscreen = false;
+			break;
 
-	default: return 0;
+	default: break;
 	}
+	return SDL_APP_CONTINUE;
 }
 
-int SDL_AppIterate(void)
+int SDL_AppIterate(void *appstate)
 {
-	DrawGLScene();           // Draw the scene
-	SDL_GL_SwapWindow(win);  // Swap buffers (Double buffering)
+	APPSTATE *state = (APPSTATE *)appstate;
+	DrawGLScene(state);             // Draw the scene
+	SDL_GL_SwapWindow(state->win);  // Swap buffers (double buffering)
 
 	// Handle keyboard input
-	const Uint8* keys = SDL_GetKeyboardState(NULL);
+	const Uint8 *keys = SDL_GetKeyboardState(NULL);
 
 	if (keys[SDL_SCANCODE_PAGEUP])
 	{
-		camera.z -= 0.02f;
+		state->camera.z -= 0.02f;
 	}
 
 	if (keys[SDL_SCANCODE_PAGEDOWN])
 	{
-		camera.z += 0.02f;
+		state->camera.z += 0.02f;
 	}
 
 	const float piover180 = 0.0174532925f;
 
 	if (keys[SDL_SCANCODE_UP])
 	{
-		camera.xpos -= sinf(camera.heading * piover180) * 0.05f;
-		camera.zpos -= cosf(camera.heading * piover180) * 0.05f;
-		if (camera.walkbiasangle >= 359.0f)
+		state->camera.xpos -= sinf(state->camera.heading * piover180) * 0.05f;
+		state->camera.zpos -= cosf(state->camera.heading * piover180) * 0.05f;
+		if (state->camera.walkbiasangle >= 359.0f)
 		{
-			camera.walkbiasangle = 0.0f;
+			state->camera.walkbiasangle = 0.0f;
 		}
 		else
 		{
-			camera.walkbiasangle += 10;
+			state->camera.walkbiasangle += 10;
 		}
-		camera.walkbias = sinf(camera.walkbiasangle * piover180) / 20.0f;
+		state->camera.walkbias = sinf(state->camera.walkbiasangle * piover180) / 20.0f;
 	}
 
 	if (keys[SDL_SCANCODE_DOWN])
 	{
-		camera.xpos += sinf(camera.heading * piover180) * 0.05f;
-		camera.zpos += cosf(camera.heading * piover180) * 0.05f;
-		if (camera.walkbiasangle <= 1.0f)
+		state->camera.xpos += sinf(state->camera.heading * piover180) * 0.05f;
+		state->camera.zpos += cosf(state->camera.heading * piover180) * 0.05f;
+		if (state->camera.walkbiasangle <= 1.0f)
 		{
-			camera.walkbiasangle = 359.0f;
+			state->camera.walkbiasangle = 359.0f;
 		}
 		else
 		{
-			camera.walkbiasangle -= 10;
+			state->camera.walkbiasangle -= 10;
 		}
-		camera.walkbias = sinf(camera.walkbiasangle * piover180) / 20.0f;
+		state->camera.walkbias = sinf(state->camera.walkbiasangle * piover180) / 20.0f;
 	}
 
 	if (keys[SDL_SCANCODE_RIGHT])
 	{
-		camera.heading -= 1.0f;
-		camera.yrot = camera.heading;
+		state->camera.heading -= 1.0f;
+		state->camera.yrot = state->camera.heading;
 	}
 
 	if (keys[SDL_SCANCODE_LEFT])
 	{
-		camera.heading += 1.0f;
-		camera.yrot = camera.heading;
+		state->camera.heading += 1.0f;
+		state->camera.yrot = state->camera.heading;
 	}
 
 	if (keys[SDL_SCANCODE_PAGEUP])
 	{
-		camera.lookupdown -= 1.0f;
+		state->camera.lookupdown -= 1.0f;
 	}
 
 	if (keys[SDL_SCANCODE_PAGEDOWN])
 	{
-		camera.lookupdown += 1.0f;
+		state->camera.lookupdown += 1.0f;
 	}
 
-	return 0;
+	return SDL_APP_CONTINUE;
 }
 
-int SDL_AppInit(int argc, char *argv[])
+int SDL_AppInit(void **appstate, int argc, char *argv[])
 {
-	SDL_Init(SDL_INIT_VIDEO);
-
-	// Ask The User Which Screen Mode They Prefer
-	const SDL_MessageBoxData msgbox =
+	if (SDL_Init(SDL_INIT_VIDEO) < 0)
 	{
-		/* flags       */ SDL_MESSAGEBOX_INFORMATION,
-		/* window      */ win,
-		/* title       */ "Start FullScreen?",
-		/* message     */ "Would You Like To Run In Fullscreen Mode?",
-		/* numbuttons  */ 2,
-		/* buttons     */ yesnobttns,
-		/* colorScheme */ NULL
-	};
-	int bttnid = 1;
-	SDL_ShowMessageBox(&msgbox, &bttnid);
-
-	// Create Our OpenGL Window
-	const bool wantfullscreen = (bttnid == 0);
-	if (!CreateGLWindow("Lionel Brits & NeHe's 3D World Tutorial", 640, 480, 16, wantfullscreen))
-	{
-		return -1;           // Quit If Window Was Not Created
+		return SDL_APP_FAILURE;
 	}
 
-	camera = (CAMERA)
+	APPSTATE *state = *appstate = malloc(sizeof(APPSTATE));
+	if (!state)
 	{
-		.heading = 0.0f,
-		.xpos = 0.0f,
-		.zpos = 0.0f,
-		.yrot = 0.0f,
-		.walkbias = 0.0f,
-		.walkbiasangle = 0.0f,
-		.lookupdown = 0.0f,
-		.z = 0.0f
+		return SDL_APP_FAILURE;
+	}
+	*state = (APPSTATE)
+	{
+		.win = NULL,
+		.ctx = NULL,
+
+		.fullscreen = false,
+		.blend = false,  // Blending off
+
+		.camera = (CAMERA)
+		{
+			.heading = 0.0f,
+			.xpos = 0.0f,
+			.zpos = 0.0f,
+			.yrot = 0.0f,
+			.walkbias = 0.0f,
+			.walkbiasangle = 0.0f,
+			.lookupdown = 0.0f,
+			.z = 0.0f
+		},
+
+		.filter = 0,
+		.texture = { 0, 0, 0 },
+		.sector1 = (SECTOR){ .numtriangles = 0, .triangle = NULL }
 	};
 
-	return 0;
+	// Ask the user if they would like to start in fullscreen or windowed mode
+	int bttnid = ShowYesNoMessageBox(state->win, BTTN_NO, "Start FullScreen?",
+		"Would You Like To Run In Fullscreen Mode?");
+
+	// Create our OpenGL window
+	const bool wantfullscreen = (bttnid == BTTN_YES);
+	if (!CreateGLWindow(state, "Lionel Brits & NeHe's 3D World Tutorial", 640, 480, 16, wantfullscreen))
+	{
+		return SDL_APP_FAILURE;
+	}
+
+	return SDL_APP_CONTINUE;
 }
 
-void SDL_AppQuit()
+void SDL_AppQuit(void *appstate)
 {
-	// Shutdown
-	free(sector1.triangle);
-	if (ctx)
+	if (appstate)
 	{
-		glDeleteTextures(3, texture);
+		APPSTATE *state = (APPSTATE *)appstate;
+		free(state->sector1.triangle);
+		if (state->ctx)
+		{
+			glDeleteTextures(3, state->texture);
+		}
+		KillGLWindow(state);
+		free(state);
 	}
-	KillGLWindow();   // Kill The Window
+
 	SDL_Quit();
 }