racing_game/clouds.cpp

#include <GL/glut.h>
#include <math.h>
#include <iostream>

#include "PerlinNoise.hpp"
#include "textures.h"
#include "libs/mainloop-api/mainloop.h"
#include "random.h"
#include "math.h"

int cloud_tex;
char* cloud_data;
int cloud_dimentions[2] = {100, 100};
double cloud_fade_distance = 25;
double cloud_frequency = 32;
double cloud_time = 0;
double frequency = 10;

const siv::PerlinNoise perlin;

void clouds_init()
{
  // Setup the cloud data
  cloud_data = new char[cloud_dimentions[0]*cloud_dimentions[1]*4];

  // Fill the clouds with data
  for(int x=0;x<cloud_dimentions[0];x++) {
    for(int y=0;y<cloud_dimentions[1];y++)
    {
      // Get the id
      int id = (x*cloud_dimentions[1]+y)*4;

      // Set some noise
      cloud_data[id+0] = 255;
      cloud_data[id+1] = 255;
      cloud_data[id+2] = 255;
    }
  }
}

void clouds_move(int *args)
{
  // Make this happen again
  mainloopRegAction(clouds_move, 10, 0);

  // Add to the time
  cloud_time += 1e-3;
}

void clouds_render()
{
  // Fill the clouds with data
  for(int x=0;x<cloud_dimentions[0];x++) {
    for(int y=0;y<cloud_dimentions[1];y++)
    {
      // Get the id
      int id = (x*cloud_dimentions[1]+y)*4;

      // Get the distance between pixels
      double distance = sqrt(
        squarei(x - cloud_dimentions[0]/2) +
        squarei(y - cloud_dimentions[1]/2)
      );

      // Is the distance less than 50
      if(distance < cloud_dimentions[0]/2.0)
      {
        // Make some noise
        double n = perlin.octaveNoise0_1(
          x/cloud_frequency,
          y/cloud_frequency,
        cloud_time, 10);

        char noise;

        if(n < 0) noise = 0;
        else if(n > 1) noise = 255;
        else noise = n*255;

        // Is the distance greater than 10
        if(distance > cloud_dimentions[0]/2.0-cloud_fade_distance)
        {
          // Set distance opacity
          cloud_data[id+3] = 255-
          (distance-(cloud_dimentions[0]/2.0-cloud_fade_distance))/cloud_fade_distance*255;
        }

        else
        {
          // Set normal opacity
          cloud_data[id+3] = 255;
        }

        // Set some noise
        cloud_data[id+0] = noise;
        cloud_data[id+1] = noise;
        cloud_data[id+2] = noise;

      }

      else
      {
        // Set the opacity to zero
        cloud_data[id+3] = 0;
      }
    }
  }

  // Load the clouds texture as linear
  cloud_tex = loadPixels(cloud_data, cloud_dimentions[0], cloud_dimentions[1], 'L', false);

  // Start rendering the clouds
  glBegin(GL_QUADS);

  // Draw the clouds above the player
  glTexCoord2i(0,0); glVertex3d(-10, 1,-10);
  glTexCoord2i(1,0); glVertex3d( 10, 1,-10);
  glTexCoord2i(1,1); glVertex3d( 10, 1, 10);
  glTexCoord2i(0,1); glVertex3d(-10, 1, 10);

  // Stop rendering the clouds
  glEnd();

  // Unbind the texture
  glBindTexture(GL_TEXTURE_2D, cloud_tex);

  // Clear the depth
  glClear(GL_DEPTH_BUFFER_BIT);
}