src/app.cpp

   1 #include "app.hpp"
   2
   3 #include <iostream>
   4 #include <stdexcept>
   5
   6
   7 namespace {
   8
   9 constexpr GLfloat vtx_coords[] = {
  10         -1.0f, -1.0f, -1.0f,
  11          1.0f, -1.0f, -1.0f,
  12          0.0f,  1.0f, -1.0f,
  13 };
  14
  15 }
  16
  17 namespace blank {
  18
  19 Application::Application()
  20 : init_sdl()
  21 , init_gl()
  22 , window()
  23 , ctx(window.CreateContext())
  24 , init_glew()
  25 , program()
  26 , vtx_buf(0)
  27 , mvp()
  28 , mvp_handle(0)
  29 , running(false) {
  30         GLContext::EnableVSync();
  31         program.LoadShader(
  32                 GL_VERTEX_SHADER,
  33                 "#version 330 core\n"
  34                 "layout(location = 0) in vec3 vertexPosition_modelspace;\n"
  35                 "uniform mat4 MVP;\n"
  36                 "void main() {\n"
  37                         "vec4 v = vec4(vertexPosition_modelspace, 1);\n"
  38                         "gl_Position = MVP * v;\n"
  39                 "}\n"
  40         );
  41         program.LoadShader(
  42                 GL_FRAGMENT_SHADER,
  43                 "#version 330 core\n"
  44                 "out vec3 color;\n"
  45                 "void main() {\n"
  46                         "color = vec3(1, 1, 1);\n"
  47                 "}\n"
  48         );
  49         program.Link();
  50         if (!program.Linked()) {
  51                 program.Log(std::cerr);
  52                 throw std::runtime_error("link program");
  53         }
  54
  55         GLuint VertexArrayID;
  56         glGenVertexArrays(1, &VertexArrayID);
  57         glBindVertexArray(VertexArrayID);
  58
  59         glGenBuffers(1, &vtx_buf);
  60         glBindBuffer(GL_ARRAY_BUFFER, vtx_buf);
  61         glBufferData(GL_ARRAY_BUFFER, sizeof(vtx_coords), vtx_coords, GL_STATIC_DRAW);
  62
  63         glm::mat4 projection = glm::perspective(
  64                 45.0f, // FOV in degrees
  65                 1.0f,  // aspect ratio
  66                 0.1f,  // near clip
  67                 100.0f // far clip
  68         );
  69         glm::mat4 view = glm::lookAt(
  70                 glm::vec3(0, 0,  0),  // observer
  71                 glm::vec3(0, 0, -1), // target
  72                 glm::vec3(0, 1,  0) // up
  73         );
  74         glm::mat4 model(1.0f); // identity: no transformation
  75         mvp = projection * view * model;
  76
  77         mvp_handle = program.UniformLocation("MVP");
  78
  79         glClearColor(0.0, 0.0, 0.0, 1.0);
  80 }
  81
  82 Application::~Application() {
  83
  84 }
  85
  86
  87 void Application::Run() {
  88         running = true;
  89         Uint32 last = SDL_GetTicks();
  90         while (running) {
  91                 Uint32 now = SDL_GetTicks();
  92                 int delta = now - last;
  93                 Loop(delta);
  94                 last = now;
  95         }
  96 }
  97
  98 void Application::Loop(int dt) {
  99         HandleEvents();
 100         Render();
 101 }
 102
 103
 104 void Application::HandleEvents() {
 105         SDL_Event event;
 106         while (SDL_PollEvent(&event)) {
 107                 switch (event.type) {
 108                         case SDL_QUIT:
 109                                 running = false;
 110                                 break;
 111                         default:
 112                                 break;
 113                 }
 114         }
 115 }
 116
 117 void Application::Render() {
 118         glClear(GL_COLOR_BUFFER_BIT);
 119
 120         program.Use();
 121
 122         glUniformMatrix4fv(mvp_handle, 1, GL_FALSE, &mvp[0][0]);
 123
 124         glEnableVertexAttribArray(0);
 125         glBindBuffer(GL_ARRAY_BUFFER, vtx_buf);
 126         glVertexAttribPointer(
 127                 0,        // attribute 0 (for shader)
 128                 3,        // size
 129                 GL_FLOAT, // type
 130                 GL_FALSE, // normalized
 131                 0,        // stride
 132                 nullptr   // offset
 133         );
 134         glDrawArrays(
 135                 GL_TRIANGLES, // how
 136                 0,            // start
 137                 3             // len
 138         );
 139         glDisableVertexAttribArray(0);
 140
 141         window.Flip();
 142 }
 143
 144 }