Add perspective camera and shader-hot-swapping

shaders/alt.frag

@@ -0,0 +1,12 @@
+#version 460 core
+
+layout (location = 0) in vec4 tex_color;
+layout (location = 1) in vec2 tex_coord;
+
+out vec4 frag_color;
+
+uniform sampler2D tex;
+
+void main() {
+    frag_color = texture(tex, tex_coord) * (vec4(1.0) - tex_color);
+}

shaders/alt.vert

@@ -0,0 +1,21 @@
+#version 460 core
+
+layout (location = 0) in vec3 a_pos;
+layout (location = 1) in vec3 a_color;
+layout (location = 2) in vec2 a_tex_coord;
+
+layout (std140, binding = 0) uniform Matrices {
+    mat4 view;
+    mat4 projection;
+};
+
+layout (location = 0) out vec4 tex_color;
+layout (location = 1) out vec2 tex_coord;
+
+void main() {
+    vec3 offset = vec3(0.0, 0.0, -1.0);
+    gl_Position = projection * view * vec4(a_pos + offset, 1.0);
+    tex_color = vec4(a_color, 1.0);
+    tex_coord = a_tex_coord;
+}
+

shaders/basic.vert

@@ -4,11 +4,16 @@ layout (location = 0) in vec3 a_pos;
 layout (location = 1) in vec3 a_color;
 layout (location = 2) in vec2 a_tex_coord;
 
+layout (std140, binding = 0) uniform Matrices {
+    mat4 view;
+    mat4 projection;
+};
+
 layout (location = 0) out vec4 tex_color;
 layout (location = 1) out vec2 tex_coord;
 
 void main() {
-    gl_Position = vec4(a_pos, 1.0);
+    gl_Position = projection * view * vec4(a_pos, 1.0);
     tex_color = vec4(a_color, 1.0);
     tex_coord = a_tex_coord;
 }

src/renderer.cpp

@@ -3,6 +3,10 @@
 
 
 bool init_renderer(Renderer *renderer, u32 width, u32 height) {
+  renderer->m_width = width;
+  renderer->m_height = height;
+  
+
   if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
     log(1, "%s error: failed to initialize GLAD\n", __FUNCTION__);
     return false;
@@ -40,12 +44,29 @@ bool init_renderer(Renderer *renderer, u32 width, u32 height) {
   }
 
   {
-    bool success = load_shaders(&renderer->shader, "shaders/basic.vert", "shaders/basic.frag");
+    bool success = init_uniform_buffer(&renderer->uniform_buffer);
     if (!success) {
-      log(1, "%s: shader loading failed\n", __FUNCTION__);
+      log(1, "%s: uniform buffer successfully created\n", __FUNCTION__);
       return false;
     }
-    log(1, "%s: shaders succesfully loaded\n", __FUNCTION__);
+  }
+
+  {
+    bool success = load_shaders(&renderer->shader, "shaders/basic.vert", "shaders/basic.frag");
+    if (!success) {
+      log(1, "%s: basic shader loading failed\n", __FUNCTION__);
+      return false;
+    }
+    log(1, "%s: basic shaders succesfully loaded\n", __FUNCTION__);
+  }
+
+  {
+    bool success = load_shaders(&renderer->alt_shader, "shaders/alt.vert", "shaders/alt.frag");
+    if (!success) {
+      log(1, "%s: alt shader loading failed\n", __FUNCTION__);
+      return false;
+    }
+    log(1, "%s: alt shaders succesfully loaded\n", __FUNCTION__);
   }
 
   return true;
@@ -66,13 +87,30 @@ void draw_renderer(Renderer *renderer) {
   glEnable(GL_CULL_FACE);
   glEnable(GL_DEPTH_TEST);
 
-  use_shader(&renderer->shader);
+  Vector3 camera_position = Vector3(0.4f, 0.3f, 1.0f);
+  Vector3 camera_look_at_position = Vector3(0.0f, 0.0f, 0.0f);
+  Vector3 camera_up_vector = Vector3(0.0f, 1.0f, 0.0f);
+
+  renderer->projection_matrix = glm::perspective(glm::radians(90.0f), static_cast<f32>(renderer->m_width) / static_cast<f32>(renderer->m_height), 0.1f, 100.0f);
+
+  f32 dt = glfwGetTime();
+  Matrix4 model = Matrix4(1.0);
+
+  if (!renderer->use_alt_shader) {
+    use_shader(&renderer->shader);
+    model = glm::rotate(Matrix4(1.0f), dt, Vector3(0.0f, 0.0f, 1.0f));
+  } else {
+    use_shader(&renderer->alt_shader);
+    model = glm::rotate(Matrix4(1.0f), -dt, Vector3(0.0f, 0.0f, 1.0f));
+  }
+
+  renderer->view_matrix = glm::lookAt(camera_position, camera_look_at_position, camera_up_vector) * model;
+  
+  upload_uniform_buffer_data(&renderer->uniform_buffer, renderer->view_matrix, renderer->projection_matrix);
 
   bind_texture(&renderer->texture);
-
   bind_vertex_buffer(&renderer->vertex_buffer);
 
-
   draw_vertex_buffer(GL_TRIANGLES, 0, renderer->triangle_count * 3);
 
   unbind_vertex_buffer();
@@ -89,6 +127,7 @@ void upload_renderer_data(Renderer *renderer, Mesh *vertex_data) {
 
 void cleanup_renderer(Renderer *renderer) {
   cleanup_shader(&renderer->shader);
+  cleanup_shader(&renderer->alt_shader);
   cleanup_texture(&renderer->texture);
   cleanup_vertex_buffer(&renderer->vertex_buffer);
   cleanup_frame_buffer(&renderer->frame_buffer);
@@ -231,6 +270,30 @@ void draw_vertex_buffer(u32 mode, u32 start, u32 num) {
   glDrawArrays(mode, start, num);
 }
 
+/*
+ * Uniform buffer
+ */
+bool init_uniform_buffer(Uniform_Buffer *uniform_buffer) {
+  glGenBuffers(1, &uniform_buffer->ubo_buffer);
+  glBindBuffer(GL_UNIFORM_BUFFER, uniform_buffer->ubo_buffer);
+  glBufferData(GL_UNIFORM_BUFFER, 2 * sizeof(Matrix4), nullptr, GL_STATIC_DRAW);
+  glBindBuffer(GL_UNIFORM_BUFFER, 0);
+
+  return true;
+}
+
+void upload_uniform_buffer_data(Uniform_Buffer *uniform_buffer, Matrix4 view_matrix, Matrix4 projection_matrix) {
+  glBindBuffer(GL_UNIFORM_BUFFER, uniform_buffer->ubo_buffer);
+  glBufferSubData(GL_UNIFORM_BUFFER, 0, sizeof(Matrix4), glm::value_ptr(view_matrix));
+  glBufferSubData(GL_UNIFORM_BUFFER, sizeof(Matrix4), sizeof(Matrix4), glm::value_ptr(projection_matrix));
+  glBindBufferRange(GL_UNIFORM_BUFFER, 0, uniform_buffer->ubo_buffer, 0, 2 * sizeof(Matrix4));
+  glBindBuffer(GL_UNIFORM_BUFFER, 0);
+}
+
+void cleanup(Uniform_Buffer *uniform_buffer) {
+  glDeleteBuffers(1, &uniform_buffer->ubo_buffer);
+}
+
 
 /*
  * Texture
@@ -304,6 +367,9 @@ bool load_shaders(Shader *shader, string vertex_shader_filepath, string fragment
     return false;
   }
 
+  s32 ubo_index = glGetUniformBlockIndex(shader->program, "Matrices");
+  glUniformBlockBinding(shader->program, ubo_index, 0);
+
   glDeleteShader(vertex_shader);
   glDeleteShader(fragment_shader);
 

src/renderer.h

@@ -7,6 +7,7 @@
 #include <glad/glad.h>
 #include <GLFW/glfw3.h>
 #include <stb_image.h>
+#include <glm/gtc/type_ptr.hpp>
 
 
 struct Vertex {
@@ -32,6 +33,10 @@ struct Vertex_Buffer {
   u32 vbo = 0;
 };
 
+struct Uniform_Buffer {
+  u32 ubo_buffer = 0;
+};
+
 struct Texture {
   u32 texture = 0;
   s32 width = 0;
@@ -44,14 +49,20 @@ struct Shader {
   u32 program = 0;
 };
 
-
 struct Renderer {
   Shader shader;
+  Shader alt_shader;
   Frame_Buffer frame_buffer;
   Vertex_Buffer vertex_buffer;
+  Uniform_Buffer uniform_buffer;
   Texture texture;
   Mesh mesh;
   s32 triangle_count = 0;
+  bool use_alt_shader = false;
+  Matrix4 view_matrix = Matrix4(1.0f);
+  Matrix4 projection_matrix = Matrix4(1.0f);
+  u32 m_width = 0;
+  u32 m_height = 0;
 };
 
 
@@ -76,6 +87,10 @@ void bind_vertex_buffer(Vertex_Buffer *vertex_buffer);
 void unbind_vertex_buffer();
 void draw_vertex_buffer(u32 mode, u32 start, u32 num);
 
+bool init_uniform_buffer(Uniform_Buffer *uniform_buffer);
+void upload_uniform_buffer_data(Uniform_Buffer *uniform_buffer, Matrix4 view_matrix, Matrix4 projection_matrix);
+void cleanup(Uniform_Buffer *uniform_buffer);
+
 bool load_texture(Texture *texture, string filepath);
 void bind_texture(Texture *texture);
 void unbind_texture();

src/window.cpp

@@ -82,25 +82,9 @@ void handle_close(GLFWwindow *gl_window) {
 void handle_key_events(GLFWwindow *gl_window, s32 key, s32 scancode, s32 action, s32 mods) {
   Window *window = static_cast<Window *>(glfwGetWindowUserPointer(gl_window));
 
-  string action_name;
-
-  switch(action) {
-    case GLFW_PRESS:
-      action_name = "pressed";
-      break;
-    case GLFW_RELEASE:
-      action_name = "released";
-      break;
-    case GLFW_REPEAT:
-      action_name = "repeated";
-      break;
-    default:
-      action_name = "invalid";
-      break;
+  if (glfwGetKey(window->glfw_window, GLFW_KEY_SPACE) == GLFW_PRESS) {
+    window->renderer->use_alt_shader = !window->renderer->use_alt_shader;
   }
-
-  const char *key_name = glfwGetKeyName(key, 0);
-  log(1, "%s: key %s (key %i, scancode %i) %s\n", __FUNCTION__, key_name, key, scancode, action_name.c_str());
 }
 
 void handle_mouse_position_events(GLFWwindow *gl_window, f64 x_pos, f64 y_pos) {