dos-vga-arena-shooter-game/system/vga.c

#include "vga.h"
#include "pc_stuff.h"
#include <malloc.h>
#include <conio.h>
#include <string.h>
#include <stdio.h>
#include <time.h>

int activePage = 0;
byte *drawBuffer;

byte *initializeDrawBuffer() {
  int i;

  drawBuffer = (byte *)malloc(VGA_DISPLAY_WIDTH * VGA_DISPLAY_HEIGHT);

  for (i = 0; i < VGA_DISPLAY_WIDTH * VGA_DISPLAY_HEIGHT; ++i) {
    drawBuffer[i] = 0;
  }

  return drawBuffer;
}

void copyDrawBufferToDisplay() {
  memcpy(VGA, drawBuffer, VGA_DISPLAY_WIDTH * VGA_DISPLAY_HEIGHT);
}

void freeDrawBuffer() {
  free(drawBuffer);
}

byte *getDrawBuffer() {
  return drawBuffer;
}

clock_t startTime, endTime;

void buildSpriteFromSpritesheet(
  struct BMPImage *spritesheetImage,
  struct SpriteRender *spriteRender,
  int positionX,
  int positionY,
  int width,
  int height
) {
  spriteRender->data = spritesheetImage->memoryStart + positionY * spritesheetImage->width + positionX;
  spriteRender->modulo = spritesheetImage->width - width;
  spriteRender->width = width;
  spriteRender->height = height;
  spriteRender->transparentColor = spritesheetImage->transparentColor;
}

void drawPixel(int x, int y, int color) {
  drawBuffer[y * VGA_DISPLAY_WIDTH + x] = color;
}

void drawSprite(struct SpriteRender* sprite) {
  int x, y;
  byte pixel;
  int modulo = VGA_DISPLAY_WIDTH - sprite->width;

  byte* spriteData = sprite->data;
  byte* drawBufferPos =
    drawBuffer +
    sprite->x -
    sprite->offsetX +
    (
      (sprite->y - sprite->offsetY) * VGA_DISPLAY_WIDTH
    );

  for (y = 0; y < sprite->height; ++y) {
    for (x = 0; x < sprite->width; ++x) {
      pixel = *(spriteData++);
      if (pixel != sprite->transparentColor) {
        *(drawBufferPos) = pixel;
      }

      drawBufferPos++;
    }

    drawBufferPos += modulo;
    spriteData += sprite->modulo;
  }
}

void getSpriteBounds(struct SpriteRender *sprite, struct SpriteBounds *bounds) {
  bounds->top = sprite->y - sprite->offsetY;
  bounds->bottom = bounds->top + sprite->height;

  bounds->left = sprite->x - sprite->offsetX;
  bounds->right = bounds->left + sprite->width;
}

void setVGAColors(struct VGAColor colors[], int totalColors) {
  int i;

  outp(0x3c8,0);
  for (i = 0; i < totalColors; ++i) {
    outp(0x3c9, colors[i].red);
    outp(0x3c9, colors[i].green);
    outp(0x3c9, colors[i].blue);
  }
}