Created a camera system that has changing mvp and setting the uniform

Now to correct whatever is wrong with it.

CMakeLists.txt

@@ -88,6 +88,7 @@ target_include_directories(${PROJECT_NAME} PRIVATE
 )
 
 target_link_libraries(${PROJECT_NAME} PRIVATE
+    m
     ${SDL3_LIBRARIES}
     ${SDL3_image_LIBRARIES}
     ${CGLM_LIBRARIES}

shaders/vert.glsl

@@ -1,8 +1,10 @@
 #version 330 core
 layout (location = 0) in vec3 aPos;
 
+uniform mat4 MVP;
+
 void main()
 {
-  gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);
+  gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0) * MVP;
 }
 

src/camera.c

@@ -0,0 +1,87 @@
+#include "camera.h"
+#include "SDL3/SDL_keyboard.h"
+#include "cglm/mat4.h"
+#include "cglm/cam.h"
+#include "cglm/vec3.h"
+#include <SDL3/SDL_mouse.h>
+#include <cglm/util.h>
+#include <math.h>
+
+static float mouse_x, mouse_y;
+
+Camera Camera_default = {
+  .position = {0.0f, 0.0f, 3.0f},
+  .forward = {0.0f, 0.0f, -1.0f},
+  .yaw = -1.5707963268f, // -90 deg in radians
+  .pitch = 0
+};
+
+void camera_tick(Camera *camera) {
+  // Mouse input
+  SDL_GetRelativeMouseState(&mouse_x, &mouse_y);
+  camera->yaw += mouse_x * glm_rad(MOUSE_SENSITIVITY);
+  camera->pitch += mouse_y * glm_rad(MOUSE_SENSITIVITY);
+  // Restrict pitch
+  if (camera->pitch > 89.0f)
+    camera->pitch = 89.0f;
+  if (camera->pitch < -89.0f)
+    camera->pitch = -89.0f;
+
+  // Camera Direction
+  camera->forward[0] = cos(camera->yaw) * cos(camera->pitch);
+  camera->forward[1] = sin(camera->pitch);
+  camera->forward[2] = sin(camera->yaw) * cos(camera->pitch);
+  glm_normalize(camera->forward);
+  vec3 camera_right = GLM_VEC3_ZERO_INIT;
+  vec3 up = GLM_VEC3_ZERO_INIT;
+  up[2] = 1.0f;
+  glm_cross(up, camera->forward, camera_right);
+  glm_normalize(camera_right);
+
+  // Move camera based on wasd;
+  const bool *keyboardState = SDL_GetKeyboardState(NULL);
+  if (keyboardState[SDL_SCANCODE_W]) {
+    vec3 calc_buff;
+    glm_vec3_scale(camera->forward, MOVEMENT_SPEED, calc_buff);
+    glm_vec3_add(camera->position, calc_buff, camera->position);
+  }
+  if (keyboardState[SDL_SCANCODE_S]) {
+    vec3 calc_buff;
+    glm_vec3_scale(camera->forward, MOVEMENT_SPEED, calc_buff);
+    glm_vec3_sub(camera->position, calc_buff, camera->position);
+  }
+  if (keyboardState[SDL_SCANCODE_A]) {
+    vec3 calc_buff;
+    glm_vec3_scale(camera_right, MOVEMENT_SPEED, calc_buff);
+    glm_vec3_add(camera->position, calc_buff, camera->position);
+  }
+  if (keyboardState[SDL_SCANCODE_D]) {
+    vec3 calc_buff;
+    glm_vec3_scale(camera_right, MOVEMENT_SPEED, calc_buff);
+    glm_vec3_sub(camera->position, calc_buff, camera->position);
+  }
+}
+
+void calc_camera_mvp(mat4 *mvp_result, Camera *camera) {
+  // Get position to look and up vector
+  vec3 camera_target;
+  glm_vec3_add(camera->position , camera->forward, camera_target);
+  vec3 up = GLM_VEC3_ZERO_INIT;
+  up[2] = 1.0f;
+
+  mat4 model;
+  glm_mat4_identity(model);
+
+  mat4 view;
+  glm_lookat(camera->position, camera_target, up, view);
+
+  mat4 projection;
+  float fov = glm_rad(45.0f); // fov y
+  float aspect = 800.0f / 600.0f;
+  float near = 0.1f;
+  float far = 100.0f;
+  glm_perspective(fov, aspect, near, far, projection);
+
+  glm_mat4_mul(model, view, *mvp_result);
+  glm_mat4_mul(*mvp_result, projection, *mvp_result);
+}

src/camera.h

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <cglm/types.h>
+
+#define MOVEMENT_SPEED 0.02f
+#define MOUSE_SENSITIVITY 0.05f
+
+struct Camera_s {
+  vec3 position;
+  vec3 forward;
+  float yaw;
+  float pitch;
+};
+typedef struct Camera_s Camera;
+extern Camera Camera_default;
+
+void calc_camera_mvp (mat4 *mvp_result, Camera *camera);
+
+void get_camera_position (vec3 *position_result, Camera *camera);
+
+void camera_tick(Camera *camera);

src/main.c

@@ -3,9 +3,11 @@
 #include <SDL3/SDL_render.h>
 #include <SDL3/SDL_video.h>
 #include <GL/glew.h>
+#include <stdio.h>
 #include <stdlib.h>
 
-#include "arena_allocator.h"
+#include "camera.h"
+#include "cglm/io.h"
 
 // settings
 const unsigned int SCR_WIDTH = 800;
@@ -142,6 +144,9 @@ int main(int argc, char *argv[]) {
   // VBOs) when it's not directly necessary.
   glBindVertexArray(0);
 
+  // Initialise camera
+  Camera camera = Camera_default;
+
   while (1) {
     // handle input
     SDL_PollEvent(&event);
@@ -149,6 +154,16 @@ int main(int argc, char *argv[]) {
       break;
     }
 
+    // Handle camera
+    camera_tick(&camera);
+
+    // TODO: make shader file
+    mat4 mvp;
+    calc_camera_mvp(&mvp, &camera);
+    glm_mat4_print(mvp,stdout);
+    int mvp_uniform_location = glGetUniformLocation(shaderProgram, "MVP");
+    glUniformMatrix4fv(mvp_uniform_location, 1, GL_FALSE, &mvp[0][0]);
+
     // render
     glClearColor(0.1f, 0.3f, 0.4f, 1.f);
     glClear(GL_COLOR_BUFFER_BIT);