voxel-test/main.c

// adapted from
// https://github.com/glfw/glfw/blob/master/examples/triangle-opengl.c

#define GLAD_GL_IMPLEMENTATION
#include "gl.h"
#define GLFW_INCLUDE_NONE
#include <GLFW/glfw3.h>

#include "const.h"
#include "cubes.h"
#include "linmath.h"
#include "stb_image.h"
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>

static const char *vertex_shader_text =
    "#version 330\n"
    "layout (location = 0) in vec3 vPos;"
    //"layout (location = 1) in vec3 vOff;"
    "uniform mat4 MVP;\n"
    "out vec2 vTex;\n"
    "void main()\n"
    "{\n"
    "    gl_Position = MVP * vec4(vPos, 1.0);\n"
    "    vTex=0.5*vPos.xy + vec2(0.5,0);\n"
    "}\n";

static const char *fragment_shader_text =
    "#version 330\n"
    "out vec4 color;\n"
    "in vec2 vTex;\n"
    "uniform sampler2D texSampler;\n"
    "void main()\n"
    "{\n"
    //"    color=vec4(vTex.rg,0.5,0.5);\n"
    "    color=vec4(texture(texSampler, vTex).rg+vTex/10.0,0.5,0.5);\n"
    "}\n";

static void key_callback(GLFWwindow *window, int key, int scancode, int action,
                         int mods) {
  if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
    glfwSetWindowShouldClose(window, GLFW_TRUE);
}

double cx = 0;
double cy = 0;
int width, height;

static void cursor_position_callback(GLFWwindow *window, double x, double y) {
  cx = (x-width/2.0) / -1000.0;
  cy = (y-height/2.0) / -1000.0;
  cy = (cy > M_PI / 2) ? M_PI / 2 : ((cy < -M_PI / 2) ? -M_PI / 2 : cy);
  return;
}

int main(void) {
  if (!glfwInit())
    exit(EXIT_FAILURE);

  glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
  glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
  glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

  GLFWwindow *window =
      glfwCreateWindow(640, 480, "OpenGL Triangle", NULL, NULL);
  if (!window) {
    glfwTerminate();
    exit(EXIT_FAILURE);
  }

  glfwMakeContextCurrent(window);
  gladLoadGL(glfwGetProcAddress);
  glfwSwapInterval(1);

  Vertex *cube = malloc(CTRI_ALL);
  gen_cubes(cube, 0, 0, 0);

  GLuint vertex_buffer;
  glGenBuffers(1, &vertex_buffer);
  glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
  glBufferData(GL_ARRAY_BUFFER, CTRI_ALL, cube, GL_STATIC_DRAW);

  GLuint vertex_shader = glCreateShader(GL_VERTEX_SHADER);
  glShaderSource(vertex_shader, 1, &vertex_shader_text, NULL);
  glCompileShader(vertex_shader);

  GLuint fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
  glShaderSource(fragment_shader, 1, &fragment_shader_text, NULL);
  glCompileShader(fragment_shader);

  GLuint program = glCreateProgram();
  glAttachShader(program, vertex_shader);
  glAttachShader(program, fragment_shader);
  glLinkProgram(program);

  GLint tex_location = glGetUniformLocation(program, "texSampler");
  GLint vpos_location = 0;
  GLint mvp_location = glGetUniformLocation(program, "MVP");

  GLuint vertex_array;
  glGenVertexArrays(1, &vertex_array);
  glBindVertexArray(vertex_array);

  glEnableVertexAttribArray(vpos_location);
  glVertexAttribPointer(vpos_location, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex),
                        (void *)0);

  unsigned char pixels[1024 * 1024 * 3];

  for (int i = 0; i < 1024 * 1024 * 3; i++) {
    pixels[i] = i * 69420;
  }

  glClearColor(0.2f, 0.5f, 0.7f, 1.0f);
  glEnable(GL_TEXTURE_2D);
  glEnable(GL_DEPTH_TEST);

  glfwSetKeyCallback(window, key_callback);
  glfwSetCursorPosCallback(window, cursor_position_callback);

  vec3 pos = {0, 0, 0};

  int x = 0, y = 25, z = 0;

  while (!glfwWindowShouldClose(window)) {
    glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);

    glfwGetFramebufferSize(window, &width, &height);
    const float ratio = width / (float)height;

    glViewport(0, 0, width, height);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glUseProgram(program);

    glBindTexture(GL_TEXTURE_2D, GL_TEXTURE0);

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 16, 16, 0, GL_RGB,
                 GL_UNSIGNED_BYTE, pixels);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

    mat4x4 m, v, p, mvp;
    mat4x4_identity(m);
    mat4x4_perspective(p, 45.0 / 180.0 * M_PI, ratio, 0.1, 1000);

    vec3 direction = {cosf(cy) * sinf(cx), sinf(cy), cosf(cy) * cosf(cx)};
    vec3 right = {sinf(cx - 3.14f / 2.0f), 0, cosf(cx - 3.14f / 2.0f)};

    if (glfwGetKey(window, GLFW_KEY_SPACE) == GLFW_PRESS) {
      vec3_add(pos, pos, direction);
    }

    if (glfwGetKey(window, GLFW_KEY_LEFT_SHIFT) == GLFW_PRESS) {
      vec3_sub(pos, pos, direction);
    }

    if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS) {
      vec3_add(pos, pos, right);
    }

    if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS) {
      vec3_sub(pos, pos, right);
    }

    vec3 dir_pos;
    vec3_add(dir_pos, direction, pos);

    vec3 up = {0,1,0};
    //vec3_mul_cross(up, right, direction);
    mat4x4_look_at(v, pos, dir_pos, up);

    mat4x4_mul(mvp, p, v);
    mat4x4_mul(mvp, mvp, m);

    glUniformMatrix4fv(mvp_location, 1, GL_FALSE, (const GLfloat *)&mvp);
    glBindVertexArray(vertex_array);

    glDrawArrays(GL_TRIANGLES, 0, BLOCK_ALL * 18);

    glfwSwapBuffers(window);
    glfwPollEvents();
  }

  free(cube);

  glfwDestroyWindow(window);

  glfwTerminate();
  exit(EXIT_SUCCESS);
}