src/main.cpp

   1 #include <iostream>
   2 #include <SDL.h>
   3 #include <GL/glew.h>
   4 #include <glm/glm.hpp>
   5 #include <glm/gtc/matrix_transform.hpp>
   6
   7 #include "init.hpp"
   8 #include "shader.hpp"
   9
  10 using namespace std;
  11 using namespace blank;
  12
  13
  14 constexpr GLfloat vtx_coords[] = {
  15         -1.0f, -1.0f, -1.0f,
  16          1.0f, -1.0f, -1.0f,
  17          0.0f,  1.0f, -1.0f,
  18 };
  19
  20
  21 int main(int argc, char *argv[]) {
  22
  23         InitSDL init_sdl;
  24         InitGL init_gl;
  25         Window window;
  26
  27         GLContext ctx = window.CreateContext();
  28         InitGLEW init_glew;
  29         GLContext::EnableVSync();
  30
  31
  32         Shader vtx_shader(GL_VERTEX_SHADER);
  33         vtx_shader.Source(
  34                 "#version 330 core\n"
  35                 "layout(location = 0) in vec3 vertexPosition_modelspace;\n"
  36                 "uniform mat4 MVP;\n"
  37                 "void main() {\n"
  38                         "vec4 v = vec4(vertexPosition_modelspace, 1);\n"
  39                         "gl_Position = MVP * v;\n"
  40                 "}\n"
  41         );
  42         vtx_shader.Compile();
  43
  44         if (!vtx_shader.Compiled()) {
  45                 cerr << "vertex shader compile error" << endl;
  46                 vtx_shader.Log(cerr);
  47                 return 4;
  48         }
  49
  50         Shader frag_shader(GL_FRAGMENT_SHADER);
  51         frag_shader.Source(
  52                 "#version 330 core\n"
  53                 "out vec3 color;\n"
  54                 "void main() {\n"
  55                         "color = vec3(1, 1, 1);\n"
  56                 "}\n"
  57         );
  58         frag_shader.Compile();
  59
  60         if (!frag_shader.Compiled()) {
  61                 cerr << "fragment shader compile error" << endl;
  62                 frag_shader.Log(cerr);
  63                 return 4;
  64         }
  65
  66
  67         Program program;
  68         program.Attach(vtx_shader);
  69         program.Attach(frag_shader);
  70         program.Link();
  71
  72         if (!program.Linked()) {
  73                 cerr << "program link error" << endl;
  74                 program.Log(cerr);
  75                 return 4;
  76         }
  77
  78
  79         GLuint VertexArrayID;
  80         glGenVertexArrays(1, &VertexArrayID);
  81         glBindVertexArray(VertexArrayID);
  82
  83
  84         GLuint vtx_buf;
  85         glGenBuffers(1, &vtx_buf);
  86         glBindBuffer(GL_ARRAY_BUFFER, vtx_buf);
  87         glBufferData(GL_ARRAY_BUFFER, sizeof(vtx_coords), vtx_coords, GL_STATIC_DRAW);
  88
  89
  90         glm::mat4 projection = glm::perspective(
  91                 45.0f, // FOV in degrees
  92                 1.0f,  // aspect ratio
  93                 0.1f,  // near clip
  94                 100.0f // far clip
  95         );
  96         glm::mat4 view = glm::lookAt(
  97                 glm::vec3(0, 0,  0),  // observer
  98                 glm::vec3(0, 0, -1), // target
  99                 glm::vec3(0, 1,  0) // up
 100         );
 101         glm::mat4 model(1.0f); // identity: no transformation
 102         glm::mat4 mvp = projection * view * model;
 103
 104         GLuint mvp_id = program.UniformLocation("MVP");
 105
 106
 107         glClearColor(0.0, 0.0, 0.0, 1.0);
 108
 109
 110         bool running = true;
 111         Uint32 last = SDL_GetTicks();
 112         while (running) {
 113                 Uint32 now = SDL_GetTicks();
 114                 int delta = now - last;
 115
 116                 SDL_Event event;
 117                 while (SDL_PollEvent(&event)) {
 118                         switch (event.type) {
 119                                 case SDL_QUIT:
 120                                         running = false;
 121                                         break;
 122                                 default:
 123                                         break;
 124                         }
 125                 }
 126
 127                 glClear(GL_COLOR_BUFFER_BIT);
 128
 129                 program.Use();
 130
 131                 glUniformMatrix4fv(mvp_id, 1, GL_FALSE, &mvp[0][0]);
 132
 133                 glEnableVertexAttribArray(0);
 134                 glBindBuffer(GL_ARRAY_BUFFER, vtx_buf);
 135                 glVertexAttribPointer(
 136                         0,        // attribute 0 (for shader)
 137                         3,        // size
 138                         GL_FLOAT, // type
 139                         GL_FALSE, // normalized
 140                         0,        // stride
 141                         nullptr   // offset
 142                 );
 143                 glDrawArrays(
 144                         GL_TRIANGLES, // how
 145                         0,            // start
 146                         3             // len
 147                 );
 148                 glDisableVertexAttribArray(0);
 149
 150                 window.Flip();
 151
 152                 last = now;
 153         }
 154
 155         return 0;
 156
 157 }