opengl-cube/glitch_cube.c

// $ gcc -o glitch_cube glitch_cube.c -lglfw -lGL -lGLU
#include <GLFW/glfw3.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

void cubeFaceX(float side) {
  glNormal3f(side, 0.0f, 0.0f);
  glTexCoord2f(0.0f, 0.0f); glVertex3f(side, -1.0f, -1.0f);
  glTexCoord2f(1.0f, 0.0f); glVertex3f(side,  1.0f, -1.0f);
  glTexCoord2f(1.0f, 1.0f); glVertex3f(side,  1.0f,  1.0f);
  glTexCoord2f(0.0f, 1.0f); glVertex3f(side, -1.0f,  1.0f);
}
void cubeFaceY(float side) {
  glNormal3f(0.0f, side, 0.0f);
  glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, side, -1.0f);
  glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, side, -1.0f);
  glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, side,  1.0f);
  glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, side,  1.0f);
}
void cubeFaceZ(float side) {
  glNormal3f(0.0f, 0.0f, side);
  glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, side);
  glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, side);
  glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f, side);
  glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f, side);
}

int main(int argc, const char** argv) {
  if (!glfwInit()) exit(1);

  glfwWindowHint(GLFW_DOUBLEBUFFER, GLFW_TRUE);
  glfwWindowHint(GLFW_FLOATING, GLFW_TRUE);
  glfwWindowHint(GLFW_CLIENT_API, GLFW_OPENGL_API);
  glfwWindowHint(GLFW_RED_BITS, 8);
  glfwWindowHint(GLFW_BLUE_BITS, 8);
  glfwWindowHint(GLFW_GREEN_BITS, 8);
  glfwWindowHint(GLFW_ALPHA_BITS, 0);
  glfwWindowHint(GLFW_STENCIL_BITS, 0);
  glfwWindowHint(GLFW_DEPTH_BITS, 16);

  glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
  glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);

  GLFWwindow* window = glfwCreateWindow(640, 480, "glitch_cube", NULL, NULL);
  glfwMakeContextCurrent(window);

  glClearDepth(1.0);

  glEnable(GL_DEPTH_TEST);
  glEnable(GL_TEXTURE_2D);
  glDisable(GL_CULL_FACE);

  glMatrixMode(GL_PROJECTION);
  GLfloat aspect = (GLfloat) 640 / 480;
  gluPerspective(45.0, aspect, 3.0, 1000.0);
  glMatrixMode(GL_MODELVIEW);

  /* load texture */
  GLuint texture;
  glGenTextures(1, &texture);
  glBindTexture(GL_TEXTURE_2D, texture);

  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

  int width = 64;
  int height = 64;

  FILE* file = fopen(argv[0], "rb");
  fseek(file, 0L, SEEK_END);
  int size = ftell(file);
  rewind(file);

  GLubyte* data = (GLubyte*) malloc(size);
  fread(data, 1, size, file);
  fclose(file);
  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB8, width, height, 0, GL_BGR, GL_UNSIGNED_BYTE, data);

  int frameCount = 0;
  while (!glfwWindowShouldClose(window)) {
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glPushMatrix();

    glTranslatef(0.0f, 0.0f, -30.0f);
    glRotatef(glfwGetTime() * 180.0f, 0.3f, 1.0f, 0.0f);
    glRotatef(glfwGetTime() * 79.0f, 0.7f, 0.0f, 1.7f);
    float scale = 6.0f - ((frameCount % 30) / 15.0f);
    glScalef(scale, scale, scale);

    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
    glBindTexture(GL_TEXTURE_2D, texture);

    if (frameCount % 30 == 0) {
      const GLuint formats[] = {
        GL_LUMINANCE,
        GL_RGBA,
        GL_RGB,
      };
      const GLuint bytes[] = {
        GL_UNSIGNED_BYTE,
        GL_UNSIGNED_SHORT,
        GL_BYTE,
        GL_UNSIGNED_BYTE_3_3_2,
        GL_FLOAT,
      };
      const GLuint filters[] = {
        GL_NEAREST,
        GL_NEAREST,
      };

      GLuint fmt = formats[rand() % 3];
      GLubyte* ptr = data + (rand() % size);
      GLuint byt = bytes[rand() % 5];
      GLuint fil = filters[rand() % 2];
      glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB8, width, height, 0, fmt, byt, ptr);
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, fil);
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, fil);
    }

    glColor3f(1.0, 1.0, 1.0);

    glBegin(GL_QUADS);
    cubeFaceX( 1.0f);
    cubeFaceY( 1.0f);
    cubeFaceZ( 1.0f);
    cubeFaceX(-1.0f);
    cubeFaceY(-1.0f);
    cubeFaceZ(-1.0f);
    glEnd();

    glPopMatrix();

    glfwSwapBuffers(window);
    glfwPollEvents();
    frameCount++;
  }

  free(data);

  glfwDestroyWindow(window);
  glfwTerminate();
}