Add example obj model

.gitignore

@@ -1,3 +1,4 @@
 .cache
 compile_commands.json
 tiny
+*.pam

src/img.c

@@ -0,0 +1,70 @@
+#include "img.h"
+#include "mem_arena.h"
+#include "pam.h"
+#include "utils.h"
+#include <stdbool.h>
+#include <stddef.h>
+
+#define SAMPLES_PER_PIXEL 4
+
+bool init_image(Arena *arena, Image *img) {
+  if (!arena || !img || img->width == 0 || img->height == 0) {
+    return false;
+  }
+
+  u64 size = img->width * img->height * SAMPLES_PER_PIXEL;
+  img->buf = wapp_mem_arena_alloc(arena, size);
+
+  return img->buf != NULL;
+}
+
+void set_pixel(Image *img, u64 x, u64 y, Colour colour) {
+  u64 idx = (y * img->width + x) * SAMPLES_PER_PIXEL;
+  for (u64 i = 0; i < SAMPLES_PER_PIXEL; ++i) {
+    img->buf[idx + i] = *(((u8 *)&colour) + i);
+  }
+}
+
+void clear_image(Image *img, Colour colour) {
+  for (u64 y = 0; y < img->height; ++y) {
+    for (u64 x = 0; x < img->width; ++x) {
+      set_pixel(img, x, y, colour);
+    }
+  }
+}
+
+void draw_line(Image *img, u64 x0, u64 y0, u64 x1, u64 y1, Colour colour) {
+  u64 dx = absolute((i64)x1 - (i64)x0);
+  u64 dy = absolute((i64)y1 - (i64)y0);
+  f32 t = 0.0f;
+  i64 x = 0;
+  i64 y = 0;
+
+  if (dx > dy) {
+    if (x0 > x1) {
+      swap(u64, x0, x1);
+      swap(u64, y0, y1);
+    }
+
+    for (u64 x = x0; x < x1; ++x) {
+      t = (f32)(x - x0) / (f32)(x1 - x0);
+      y = (i64)y0 + ((i64)y1 - (i64)y0) * t;
+      set_pixel(img, x, y, colour);
+    }
+  } else {
+    if (y0 > y1) {
+      swap(u64, x0, x1);
+      swap(u64, y0, y1);
+    }
+
+    for (u64 y = y0; y < y1; ++y) {
+      t = (f32)(y - y0) / (f32)(y1 - y0);
+      x = (i64)x0 + ((i64)x1 - (i64)x0) * t;
+      set_pixel(img, x, y, colour);
+    }
+  }
+}
+
+void save_image(const Image *img, const char *filename) {
+  write_p7_image(img->width, img->height, img->buf, filename);
+}

src/img.h

@@ -0,0 +1,29 @@
+#ifndef IMG_H
+#define IMG_H
+
+#include "aliases.h"
+#include "mem_arena.h"
+#include <stdbool.h>
+
+typedef struct img Image;
+struct img {
+  u64 width;
+  u64 height;
+  u8 *buf;
+};
+
+typedef struct colour Colour;
+struct colour {
+  u8 r;
+  u8 g;
+  u8 b;
+  u8 a;
+};
+
+bool init_image(Arena *arena, Image *img);
+void set_pixel(Image *img, u64 x, u64 y, Colour colour);
+void clear_image(Image *img, Colour colour);
+void draw_line(Image *img, u64 x0, u64 y0, u64 x1, u64 y1, Colour colour);
+void save_image(const Image *img, const char *filename);
+
+#endif // IMG_H

src/main.c

@@ -1,26 +1,34 @@
-#include "aliases.h"
+#include "img.h"
 #include "mem_arena.h"
 #include "mem_utils.h"
-#include "pam.h"
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
-typedef struct img Image;
+enum {
-struct img {
+  TINY_EXIT_SUCCESS,
-  u64 width;
+  TINY_EXIT_ARENA_INIT_FAILED,
-  u64 height;
+  TINY_EXIT_IMAGE_INIT_FAILED,
-  u8 *buf;
 };
 
 int main(void) {
   Arena *arena = NULL;
   if (!wapp_mem_arena_init(&arena, 10ul * 1024ul * 1024ul * 1024ul,
                            WAPP_MEM_ALLOC_RESERVE, false)) {
-    return -1;
+    return TINY_EXIT_ARENA_INIT_FAILED;
   }
 
+  Colour cyan = {.r = 0, .g = 255, .b = 255, .a = 255};
+  Colour red = {.r = 255, .g = 0, .b = 0, .a = 255};
+  Image img = {.width = 200, .height = 200};
+  if (!init_image(arena, &img)) {
+    return TINY_EXIT_IMAGE_INIT_FAILED;
+  }
+
+  clear_image(&img, cyan);
+  save_image(&img, "result.pam");
+
   wapp_mem_arena_destroy(&arena);
 
-  return 0;
+  return TINY_EXIT_SUCCESS;
 }

src/utils.c

@@ -0,0 +1,10 @@
+#include "utils.h"
+#include "aliases.h"
+
+i64 absolute(i64 value) {
+  if (value >= 0) {
+    return value;
+  }
+
+  return value * -1;
+}

src/utils.h

@@ -0,0 +1,14 @@
+#ifndef UTILS_H
+#define UTILS_H
+
+#include "aliases.h"
+#define swap(T, v0, v1)                                                        \
+  do {                                                                         \
+    T tmp = v0;                                                                \
+    v0 = v1;                                                                   \
+    v1 = tmp;                                                                  \
+  } while (0)
+
+i64 absolute(i64 value);
+
+#endif // UTILS_H