Pokitto-Raycasting/general.hpp

/**
  General definitions for Pokitto raycasting demos.

  author: Miloslav "drummyfish" Ciz
  license: CC0 1.0
*/

#ifndef RAYCAST_DEMO_GENERAL_HPP
#define RAYCAST_DEMO_GENERAL_HPP

#include "stdio.h" // for debugging raycastlibg

#define VERTICAL_FOV UNITS_PER_SQUARE // redefine camera vertical FOV

#include "raycastlib.h"
#include "Pokitto.h"

Pokitto::Core pokitto;

#define SCREEN_WIDTH 110
#define SCREEN_HEIGHT 88

#define MIDDLE_ROW (SCREEN_HEIGHT / 2)
#define MIDDLE_COLUMN (SCREEN_WIDTH / 2)

#ifndef SUBSAMPLE
#define SUBSAMPLE 2
#endif

#define SUBSAMPLED_WIDTH (SCREEN_WIDTH / SUBSAMPLE)

#define TRANSPARENT_COLOR 0b00000111

Unit zBuffer[SUBSAMPLED_WIDTH]; ///< 1D z-buffer for visibility determination.

/**
  Gets (the index of) color by specified RGB components. 

  @param r red, 3 bits (0 to 7)
  @param g green, 3 bits (0 to 7)
  @param b blue, 2 bits (0 to 3)
  @return palette index of the color
*/
inline uint8_t rgbToIndex(uint8_t r, uint8_t g, uint8_t b)
{
  return (r & 0b00000111) | ((g & 0b00000111) << 3) | ((b & 0b00000011) << 6);
}

/**
  Adds given intensity to a color.

  @param color input color
  @param intensity intensity to add, 3 bit (0 to 7)
  @return new color
*/
inline uint8_t addIntensity(uint8_t color, int intensity)
{
  uint8_t r = color & 0b00000111;
  uint8_t g = (color & 0b00111000) >> 3;
  uint8_t b = (color & 0b11000000) >> 6;

  if (intensity >= 0)
  {
    r += intensity;
    r = r > 7 ? 7 : r;

    g += intensity;
    g = g > 7 ? 7 : g;

    b += intensity / 2;
    b = b > 3 ? 3 : b;
  }
  else
  {
    intensity *= -1;
    r = (intensity > r) ? 0 : r - intensity;
    g = (intensity > g) ? 0 : g - intensity;
    intensity /= 2;
    b = intensity > b ? 0 : b - intensity;
  }

  return rgbToIndex(r,g,b);
}

/**
  Samples an image by normalized coordinates - each coordinate is in range
  0 to UNITS_PER_SQUARE (from raycastlib).
*/ 
inline uint8_t sampleImage(const unsigned char *image, Unit x, Unit y)
{
  // TODO: optimize

  x = wrap(x,UNITS_PER_SQUARE);
  y = wrap(y,UNITS_PER_SQUARE);

  int32_t index =
    image[1] * ((image[1] * x) / UNITS_PER_SQUARE) + (image[0] * y) /
    UNITS_PER_SQUARE;

  return image[2 + index];
}

void inline drawSprite(const unsigned char *sprite, int16_t x, int16_t y, Unit depth, int16_t size)
{
  // TODO: optimize

  x -= size / 2;
  y -= size / 2;

  Unit step = UNITS_PER_SQUARE / size;

  uint8_t c;

  int16_t jTo = size - max(0,y + size - 88);
  int16_t iTo = size - max(0,x + size - 110);

  for (Unit i = max(-1 * x,0); i < iTo; ++i)
  {
    int16_t xPos = x + i;

    if (zBuffer[xPos / SUBSAMPLE] <= depth)
      continue;

    for (Unit j = max(-1 * y,0); j < jTo; ++j)
    {
      c = sampleImage(sprite,(i * UNITS_PER_SQUARE) / size,(j * UNITS_PER_SQUARE) / size); 
     
      if (c != TRANSPARENT_COLOR)
        pokitto.display.drawPixel(xPos,y + j,c);
    }
  }
}

#endif