467 lines
15 KiB
Plaintext
467 lines
15 KiB
Plaintext
// First half of Ray Tracing in One Weekend, rendered to a SDL3 window rather
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// than an image file. Needs to be linked against SDL3, i.e.
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// `./cli cpu_raytracer.reid SDL3`
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import std::print;
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import std::String;
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///////////////////
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/// SDL externs ///
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///////////////////
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// Helper struct for stack allocated const sized strings, because structs are
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// easier to create uninit than arrays.
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struct SDL_Window {}
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struct SDL_Renderer {}
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struct SDL_Texture {}
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struct SDL_Event { type: u32, reserved: [u8; 124] }
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struct SDL_FRect { x: f32, y: f32, w: f32, h: f32 }
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struct SDL_Rect { x: i32, y: i32, w: i32, h: i32 }
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extern fn SDL_malloc(size: u64) -> *u8;
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extern fn SDL_Init(flags: u32) -> bool;
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extern fn SDL_Quit();
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extern fn SDL_CreateWindowAndRenderer(title: *char, width: i32, height: i32, flags: i32,
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window_out: &mut *SDL_Window, renderer_out: &mut *SDL_Renderer) -> bool;
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extern fn SDL_Delay(ms: u32);
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extern fn SDL_SetRenderDrawColor(renderer: *SDL_Renderer, r: u8, g: u8, b: u8, a: u8);
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extern fn SDL_RenderClear(renderer: *SDL_Renderer);
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extern fn SDL_RenderPresent(renderer: *SDL_Renderer);
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extern fn SDL_HasEvent(event_type: u32) -> bool;
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extern fn SDL_PollEvent(event: &mut SDL_Event) -> bool;
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extern fn SDL_PumpEvents();
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extern fn SDL_FlushEvents(min_type: u32, max_type: u32);
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extern fn SDL_GetTicks() -> u64;
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extern fn SDL_SetWindowTitle(window: *SDL_Window, title: *char) -> bool;
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extern fn SDL_CreateTexture(renderer: *SDL_Renderer,
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pixel_format: u32, texture_access: u32, width: u32, height: u32) -> *SDL_Texture;
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extern fn SDL_RenderTexture(renderer: *SDL_Renderer,
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texture: *SDL_Texture, srcfrect: &SDL_FRect, dstfrect: &SDL_FRect) -> bool;
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extern fn SDL_UpdateTexture(texture: *SDL_Texture, rect: &SDL_Rect, pixels: *u8, pitch: u32) -> bool;
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extern fn SDL_GetError() -> *char;
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extern fn SDL_GetWindowSize(window: *SDL_Window, w: &mut i32, h: &mut i32) -> bool;
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extern fn SDL_rand(max_exclusive: u32) -> u32;
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extern fn SDL_SetTextureScaleMode(texture: *SDL_Texture, scale_mode: i32) -> bool;
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extern fn SDL_sqrtf(value: f32) -> f32;
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extern fn SDL_randf() -> f32;
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extern fn SDL_powf(value: f32, power: f32) -> f32;
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// SDL error reporting helper
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fn print_sdl_error(context: *char) {
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let mut message = String::new();
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message = message + context + ": " + SDL_GetError();
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print(message);
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message.free();
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}
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/////////////////////////////////
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/// Main setup and frame loop ///
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/////////////////////////////////
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struct GameState {
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renderer: *SDL_Renderer,
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window: *SDL_Window,
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render_texture: *SDL_Texture,
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frame_counter: u32,
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last_fps_reset: u64,
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pixels: *u8,
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pixels_w: u32,
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pixels_h: u32,
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pixels_bpp: u32,
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}
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fn main() -> i32 {
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let SDL_INIT_VIDEO = 32;
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let SDL_WINDOW_RESIZABLE = 32;
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let SDL_PIXELFORMAT_RGBA8888 = 373694468;
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let SDL_PIXELFORMAT_ABGR8888 = 376840196;
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let SDL_PIXELFORMAT_RGB24 = 386930691;
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let SDL_PIXELFORMAT_BGR24 = 390076419;
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let SDL_PIXELFORMAT_RGB96_FLOAT = 454057996;
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let SDL_PIXELFORMAT_BGR96_FLOAT = 457203724;
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let SDL_TEXTUREACCESS_STREAMING = 1;
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let SDL_SCALEMODE_NEAREST = 0;
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let SDL_SCALEMODE_LINEAR = 1;
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let SDL_SCALEMODE_PIXELART = 2;
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let init_success = SDL_Init(SDL_INIT_VIDEO);
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if init_success == false {
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print_sdl_error("SDL init failed");
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return 1;
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}
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let mut window = SDL_Window::null();
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let mut renderer = SDL_Renderer::null();
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let gfx_init_success = SDL_CreateWindowAndRenderer(
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"cpu raytracer", 640, 480, SDL_WINDOW_RESIZABLE,
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&mut window, &mut renderer
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);
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if gfx_init_success == false {
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print_sdl_error("SDL renderer and window creation failed");
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return 1;
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}
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let width = 128;
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let height = 64;
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let bpp = 4;
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let render_texture = SDL_CreateTexture(renderer,
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SDL_PIXELFORMAT_ABGR8888, SDL_TEXTUREACCESS_STREAMING, width, height);
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SDL_SetTextureScaleMode(render_texture, SDL_SCALEMODE_NEAREST);
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let pixels_len = (width * height * bpp) as u64;
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let pixels = SDL_malloc(pixels_len);
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let mut game_state = GameState {
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renderer: renderer,
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window: window,
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render_texture: render_texture,
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frame_counter: 0,
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last_fps_reset: 0,
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pixels: pixels,
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pixels_w: width,
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pixels_h: height,
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pixels_bpp: bpp,
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};
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while frame_loop(&mut game_state) {}
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SDL_Quit();
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return 0;
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}
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fn frame_loop(game_state: &mut GameState) -> bool {
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let mut event = SDL_Event { type: 0, reserved: [0; 124] };
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while (SDL_PollEvent(&mut event)) {
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if event.type == 256 { // SDL_EVENT_QUIT
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return false;
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}
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}
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let mut screen_width = 0;
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let mut screen_height = 0;
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SDL_GetWindowSize(*game_state.window, &mut screen_width, &mut screen_height);
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let renderer = *game_state.renderer;
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SDL_SetRenderDrawColor(renderer, 0, 50, 90, 255);
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SDL_RenderClear(renderer);
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let w = *game_state.pixels_w;
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let h = *game_state.pixels_h;
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let bpp = *game_state.pixels_bpp;
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for y in 0..h {
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for x in 0..w {
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render_pixel(x, y, game_state);
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}
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}
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let texture_area = SDL_Rect { x: 0, y: 0, w: w as i32, h: h as i32 };
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if SDL_UpdateTexture(*game_state.render_texture, &texture_area, *game_state.pixels as *u8, bpp * w) == false {
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print_sdl_error("UpdateTexture error");
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}
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let src = SDL_FRect { x: 0.0, y: 0.0, w: w as f32, h: h as f32 };
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let aspect_ratio = src.w / src.h;
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let scaled_width = screen_height as f32 * aspect_ratio;
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let dst = SDL_FRect { x: (screen_width as f32 - scaled_width) / 2.0, y: 0.0, w: scaled_width, h: screen_height as f32 };
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if SDL_RenderTexture(renderer, *game_state.render_texture, &src, &dst) == false {
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print_sdl_error("RenderTexture error");
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}
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SDL_RenderPresent(renderer);
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SDL_Delay(1);
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*game_state.frame_counter = *game_state.frame_counter + 1;
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let t = SDL_GetTicks();
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if (t - *game_state.last_fps_reset) >= 1000 {
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let mut title = String::new();
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title = title + "cpu raytracer (" + *game_state.frame_counter as u64 + " fps)";
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SDL_SetWindowTitle(*game_state.window, title.inner);
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title.free();
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*game_state.frame_counter = 0;
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*game_state.last_fps_reset = t;
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}
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return true;
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}
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fn render_pixel(x: u32, y: u32, game_state: &mut GameState) {
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let w = *game_state.pixels_w;
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let h = *game_state.pixels_h;
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let bpp = *game_state.pixels_bpp;
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let samples = 8;
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let old_sample_weight = 0.9;
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let new_sample_weight = 0.1 / samples as f32;
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let mut rgb = vec_mul_scalar(old_sample_weight, [
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srgb_to_linear(*game_state.pixels[(x + y * w) * bpp + 0]),
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srgb_to_linear(*game_state.pixels[(x + y * w) * bpp + 1]),
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srgb_to_linear(*game_state.pixels[(x + y * w) * bpp + 2])
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]);
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for sample in 0..samples {
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rgb = vec_add(rgb, vec_mul_scalar(new_sample_weight, shade(x, y, *game_state.frame_counter, w, h)));
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}
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*game_state.pixels[(x + y * w) * bpp + 0] = linear_to_srgb(rgb[0]);
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*game_state.pixels[(x + y * w) * bpp + 1] = linear_to_srgb(rgb[1]);
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*game_state.pixels[(x + y * w) * bpp + 2] = linear_to_srgb(rgb[2]);
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*game_state.pixels[(x + y * w) * bpp + 3] = 255;
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}
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/////////////////
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/// Rendering ///
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/////////////////
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struct Ray {
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origin: [f32; 3],
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direction: [f32; 3],
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}
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struct Material {
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// 0 = lambertian diffuse
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// 1 = mirror
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type: u32,
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// Generally the "color" of the surface (linear factors of how much of each
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// color channel this surface does not absorb), but the idea is that the
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// type governs what this means.
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linear_color: [f32; 3],
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}
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struct Hit {
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hit: bool,
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front_face: bool,
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distance: f32,
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normal: [f32; 3],
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position: [f32; 3],
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material: Material,
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}
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impl Hit {
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fn none() -> Hit {
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Hit {
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hit: false, front_face: true, distance: 0.0, normal: [0.0; 3], position: [0.0; 3],
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material: Material { type: 0, linear_color: [0.0; 3] },
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}
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}
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}
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struct Sphere {
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center: [f32; 3],
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radius: f32,
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material: Material,
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}
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fn shade(x: u32, y: u32, t: u32, w: u32, h: u32) -> [f32; 3] {
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let jitter_x = SDL_randf() - 0.5;
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let jitter_y = SDL_randf() - 0.5;
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let pixel_scale = 1.0 / h as f32;
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let pixel_pos = [
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(x as f32 + jitter_x) * pixel_scale,
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1.0 - (y as f32 + jitter_y) * pixel_scale,
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-1.0
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];
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let camera_pos = [w as f32 * 0.5f32 * pixel_scale, h as f32 * 0.5f32 * pixel_scale, 0.0f32];
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let dir = vec_normalize(vec_sub(pixel_pos, camera_pos));
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let ray = Ray { origin: camera_pos, direction: dir };
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let beige_lambertian = Material { type: 0, linear_color: [0.3, 0.2, 0.1] };
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let green_lambertian = Material { type: 0, linear_color: [0.1, 0.5, 0.06] };
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let greenish_mirror = Material { type: 1, linear_color: [0.9, 1.0, 0.95] };
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let spheres = [
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// Ground
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Sphere { center: vec_sub(camera_pos, [0.0, 100001.0, 0.0]), radius: 100000.0, material: beige_lambertian },
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// Centered unit sphere
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Sphere { center: vec_add(camera_pos, [0.0, 0.0, 0.0 - 5.0]), radius: 1.0, material: green_lambertian },
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// The unit sphere on the right
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Sphere { center: vec_add(camera_pos, [2.0, 0.0, 0.0 - 6.0]), radius: 1.0, material: greenish_mirror }
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];
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return shade_world(ray, &spheres, 3);
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}
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fn shade_world(ray: Ray, spheres: &[Sphere; 3], bounces_left: u8) -> [f32; 3] {
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if bounces_left == 0 {
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return [0.0, 0.0, 0.0];
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}
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let mut closest_hit = Hit::none();
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closest_hit.distance = 100.0;
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for i in 0..3 {
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let sphere_hit = ray_sphere_closest_hit(ray, *spheres[i], [0.001, closest_hit.distance]);
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if sphere_hit.hit {
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closest_hit = sphere_hit;
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}
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}
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if closest_hit.hit {
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//return vec_mul_scalar(0.5, vec_add(closest_hit.normal, [1.0, 1.0, 1.0])); // normal
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//return vec_mul_scalar(closest_hit.distance / 10.0, [1.0, 1.0, 1.0]); // depth
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if closest_hit.material.type == 0 {
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let bounce_dir = vec_normalize(vec_add(closest_hit.normal, random_unit_vec()));
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let bounce_ray = Ray { origin: closest_hit.position, direction: bounce_dir };
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return vec_mul_componentwise(
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closest_hit.material.linear_color,
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shade_world(bounce_ray, spheres, bounces_left - 1)
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);
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} else if closest_hit.material.type == 1 {
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let bounce_dir = vec_reflect(ray.direction, closest_hit.normal);
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let bounce_ray = Ray { origin: closest_hit.position, direction: bounce_dir };
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return vec_mul_componentwise(
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closest_hit.material.linear_color,
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shade_world(bounce_ray, spheres, bounces_left - 1)
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);
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} else {
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return [1.0, 0.0, 1.0];
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}
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}
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return shade_sky(ray);
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}
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fn shade_sky(ray: Ray) -> [f32; 3] {
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let a = 0.5 * (ray.direction[1] + 1.0);
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return vec_add(
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vec_mul_scalar(1.0 - a, [1.0, 1.0, 1.0]),
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vec_mul_scalar(a, [0.5, 0.7, 1.0])
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);
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}
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// Returns the distance from the ray origin to the sphere, or -1.0 if the ray doesn't hit.
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fn ray_sphere_closest_hit(ray: Ray, sphere: Sphere, interval: [f32; 2]) -> Hit {
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let to_sphere = vec_sub(sphere.center, ray.origin);
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let h = vec_dot(ray.direction, to_sphere);
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let c = vec_length_squared(to_sphere) - sphere.radius * sphere.radius;
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let discriminant = h * h - c;
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if discriminant < 0.0 {
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return Hit::none();
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}
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let discriminant_sqrt = SDL_sqrtf(discriminant);
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let mut distance = h - discriminant_sqrt;
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if interval_surrounds(interval, distance) == false {
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distance = h + discriminant_sqrt;
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if interval_surrounds(interval, distance) == false {
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return Hit::none();
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}
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}
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let hit_position = vec_add(ray.origin, vec_mul_scalar(distance, ray.direction));
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let mut front_face = true;
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let mut normal = vec_normalize(vec_sub(hit_position, sphere.center));
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if vec_dot(normal, ray.direction) > 0.0 {
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normal = vec_mul_scalar(-1.0, normal);
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front_face = false;
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}
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return Hit {
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hit: true,
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front_face: front_face,
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distance: distance,
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normal: normal,
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position: hit_position,
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material: sphere.material,
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};
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}
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//////////////////
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/// Other math ///
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//////////////////
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fn clamp(min: f32, max: f32, value: f32) -> f32 {
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if value > max {
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return max;
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}
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if value < min {
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return min;
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}
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return value;
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}
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fn abs(f: f32) -> f32 {
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if f < 0.0 {
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return f * -1.0;
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}
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return f;
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}
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fn vec_add(lhs: [f32; 3], rhs: [f32; 3]) -> [f32; 3] {
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return [lhs[0] + rhs[0], lhs[1] + rhs[1], lhs[2] + rhs[2]];
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}
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fn vec_sub(lhs: [f32; 3], rhs: [f32; 3]) -> [f32; 3] {
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return [lhs[0] - rhs[0], lhs[1] - rhs[1], lhs[2] - rhs[2]];
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}
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fn vec_dot(lhs: [f32; 3], rhs: [f32; 3]) -> f32 {
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return lhs[0] * rhs[0] + lhs[1] * rhs[1] + lhs[2] * rhs[2];
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}
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fn vec_mul_componentwise(lhs: [f32; 3], rhs: [f32; 3]) -> [f32; 3] {
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return [lhs[0] * rhs[0], lhs[1] * rhs[1], lhs[2] * rhs[2]];
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}
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fn vec_mul_scalar(lhs: f32, rhs: [f32; 3]) -> [f32; 3] {
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return [lhs * rhs[0], lhs * rhs[1], lhs * rhs[2]];
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}
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fn vec_normalize(v: [f32; 3]) -> [f32; 3] {
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let len_reciprocal = 1.0f32 / SDL_sqrtf(vec_length_squared(v));
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return vec_mul_scalar(len_reciprocal, v);
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}
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fn vec_length_squared(v: [f32; 3]) -> f32 {
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return v[0] * v[0] + v[1] * v[1] + v[2] * v[2];
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}
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fn vec_abs(v: [f32; 3]) -> [f32; 3] {
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return [abs(v[0]), abs(v[1]), abs(v[2])];
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}
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fn vec_reflect(direction: [f32; 3], normal: [f32; 3]) -> [f32; 3] {
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return vec_sub(direction, vec_mul_scalar(2.0f32 * vec_dot(direction, normal), normal));
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}
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fn interval_surrounds(interval: [f32; 2], value: f32) -> bool {
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return (interval[0] < value) && (value < interval[1]);
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}
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fn random_unit_vec() -> [f32; 3] {
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let mut point = [
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SDL_randf() * 2.0f32 - 1.0f32,
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SDL_randf() * 2.0f32 - 1.0f32,
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SDL_randf() * 2.0f32 - 1.0f32
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];
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let mut lensq = vec_length_squared(point);
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while lensq > 1.0 {
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point = [
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SDL_randf() * 2.0f32 - 1.0f32,
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SDL_randf() * 2.0f32 - 1.0f32,
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SDL_randf() * 2.0f32 - 1.0f32
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];
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lensq = vec_length_squared(point);
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}
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let len_reciprocal = 1.0f32 / SDL_sqrtf(lensq);
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return vec_mul_scalar(len_reciprocal, point);
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}
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fn random_unit_vec_on_hemi(normal: [f32; 3]) -> [f32; 3] {
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let rand_vec = random_unit_vec();
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|
if vec_dot(rand_vec, normal) < 0.0f32 {
|
|
return vec_mul_scalar(0.0f32 - 1.0f32, rand_vec);
|
|
}
|
|
return rand_vec;
|
|
}
|
|
|
|
fn linear_to_srgb(linear: f32) -> u8 {
|
|
let mut floating_srgb = 0.0;
|
|
if linear <= 0.0031308f32 {
|
|
floating_srgb = 12.92f32 * linear;
|
|
} else {
|
|
floating_srgb = SDL_powf(linear as f32, 1.0 / 2.4) * 1.055f32 - 0.055f32;
|
|
}
|
|
let clamped = clamp(0.0, 1.0, floating_srgb);
|
|
return (clamped * 255.999) as u8;
|
|
}
|
|
|
|
fn srgb_to_linear(srgb: u8) -> f32 {
|
|
let floating_srgb = srgb as f32 / 255.0;
|
|
if floating_srgb <= 0.04045f32 {
|
|
return floating_srgb / 12.92f32;
|
|
}
|
|
return SDL_powf((floating_srgb as f32 + 0.055) / 1.055, 2.4);
|
|
}
|