square board and properly fit inside window

.gitignore

@@ -1,3 +1,4 @@
 compile_commands.json
 *.o
 cudoku
+.cache

cudoku.c

@@ -3,10 +3,10 @@
 #include "shader.h"
 
 static const float quad_vertices[] = {
-  -0.5f, 1.0f, 0.0f, // top left
-   0.5f, 1.0f, 0.0f, // top right 
-  -0.5f, -1.0f, 0.0f, // bottom left
-   0.5f, -1.0f, 0.0f, // bottom right
+  -1.0f, 1.0f, 0.0f, // top left
+   1.0f, 1.0f, 0.0f, // top right 
+  -1.0f, -1.0f, 0.0f, // bottom left
+   1.0f, -1.0f, 0.0f, // bottom right
 };
 
 static const int quad_indices[] = {
@@ -34,9 +34,18 @@ unsigned int prepare_bg_rect() {
   return vao;
 }
 
-void draw_bg_rect(Shader shader, unsigned int vao) {
+void draw_bg_rect(Shader shader, unsigned int vao, float x_scale, float y_scale) {
   use_shader(shader);
 
+  float mat[4][4] = {
+    {x_scale, 0, 0, 0},
+    {0, y_scale, 0, 0},
+    {0, 0, 1, 0},
+    {0, 0, 0, 1},
+  };
+
+  set_mat4(shader, "transform", (float *)mat);
+
   glBindVertexArray(vao);
   glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
 

cudoku.h

@@ -3,4 +3,4 @@
 #include "shader.h"
 
 unsigned int prepare_bg_rect(Shader shader);
-void draw_bg_rect(Shader shader, unsigned int vao);
+void draw_bg_rect(Shader shader, unsigned int vao, float x_scale, float y_scale);

main.c

@@ -1,6 +1,7 @@
 #include <stdbool.h>
 
 #include <glad/glx.h>
+#include <stdio.h>
 
 #include "x11.h"
 #include "cudoku.h"
@@ -12,6 +13,18 @@
 // Simply port the js algo for sudoku generation
 // Maybe after the game works fine we can use some winapi to add windows support
 
+void scale_bg_rect(int width, int height, float *x, float *y) {
+  if (width > height) {
+    float ratio = (float)height / (float)width;
+    *x = ratio;
+    *y = 1.f;
+  } else {
+    float ratio = (float)width / (float)height;
+    *x = 1.f;
+    *y = ratio;
+  }
+}
+
 Display *display;
 Window window;
 
@@ -19,7 +32,11 @@ int main() {
   int res = init_x11(&display, &window);
   if (res < 0) return 1;
 
+  // 900 is the initial width and height
   int width = 900, height = 900;
+  // scale factors for the entire board to nicely fit as a square inside
+  // the window
+  float x_scale = 1.f, y_scale = 1.f;
 
   Shader board_shader = create_shader("shaders/board_v.glsl", "shaders/board_f.glsl");
   unsigned int board_vao = prepare_bg_rect(board_shader);
@@ -37,18 +54,21 @@ int main() {
           width = xce.width;
           height = xce.height;
           resize_x11_window(display, window);
+          scale_bg_rect(xce.width, xce.height, &x_scale, &y_scale);
         }
 
-      } else if (xev.type == KeyPress && XLookupKeysym(&xev.xkey, 0) == XK_Escape) {
-        quit = true;
-        break;
+      } else if (xev.type == KeyPress) {
+        if (XLookupKeysym(&xev.xkey, 0) == XK_Escape || XLookupKeysym(&xev.xkey, 0) == XK_q) {
+          quit = true;
+          break;
+        }
       }
     }
 
     glClearColor(0.0, 0.0, 0.0, 1.0);
     glClear(GL_COLOR_BUFFER_BIT);
 
-    draw_bg_rect(board_shader, board_vao);
+    draw_bg_rect(board_shader, board_vao, x_scale, y_scale);
 
     glXSwapBuffers(display, window);
   }

shader.c

@@ -81,3 +81,8 @@ void use_shader(Shader shader) {
   glUseProgram(shader.program);
 }
 
+void set_mat4(Shader shader, const char *name, float *mat4) {
+  int loc = glGetUniformLocation(shader.program, name);
+  glUniformMatrix4fv(loc, 1, GL_FALSE, mat4);
+}
+

shader.h

@@ -7,3 +7,4 @@ typedef struct Shader {
 void read_shader_file(const char *path, char **buf);
 Shader create_shader(const char *vertex_path, const char *fragment_path);
 void use_shader(Shader shader);
+void set_mat4(Shader shader, const char *name, float *mat);

shaders/board_v.glsl

@@ -1,6 +1,8 @@
 #version 330 core
 layout (location = 0) in vec3 aPos;
 
+uniform mat4 transform;
+
 void main() {
-  gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);
+  gl_Position = transform * vec4(aPos, 1.0f);
 }