/**
* The PNG Heightmap loader.
*/
static void ReadHeightmapPNGImageData(byte *map, png_structp png_ptr, png_infop info_ptr)
{
uint x, y;
byte gray_palette[256];
png_bytep *row_pointers = nullptr;
bool has_palette = png_get_color_type(png_ptr, info_ptr) == PNG_COLOR_TYPE_PALETTE;
uint channels = png_get_channels(png_ptr, info_ptr);
/* Get palette and convert it to grayscale */
if (has_palette) {
int i;
int palette_size;
png_color *palette;
bool all_gray = true;
png_get_PLTE(png_ptr, info_ptr, &palette, &palette_size);
for (i = 0; i < palette_size && (palette_size != 16 || all_gray); i++) {
all_gray &= palette[i].red == palette[i].green && palette[i].red == palette[i].blue;
gray_palette[i] = RGBToGrayscale(palette[i].red, palette[i].green, palette[i].blue);
}
/**
* For a non-gray palette of size 16 we assume that
* the order of the palette determines the height;
* the first entry is the sea (level 0), the second one
* level 1, etc.
*/
if (palette_size == 16 && !all_gray) {
for (i = 0; i < palette_size; i++) {
gray_palette[i] = 256 * i / palette_size;
}
}
}
row_pointers = png_get_rows(png_ptr, info_ptr);
/* Read the raw image data and convert in 8-bit grayscale */
for (x = 0; x < png_get_image_width(png_ptr, info_ptr); x++) {
for (y = 0; y < png_get_image_height(png_ptr, info_ptr); y++) {
byte *pixel = &map[y * png_get_image_width(png_ptr, info_ptr) + x];
uint x_offset = x * channels;
if (has_palette) {
*pixel = gray_palette[row_pointers[y][x_offset]];
} else if (channels == 3) {
*pixel = RGBToGrayscale(row_pointers[y][x_offset + 0],
row_pointers[y][x_offset + 1], row_pointers[y][x_offset + 2]);
} else {
*pixel = row_pointers[y][x_offset];
}
}
}
}
/**
* The BMP Heightmap loader.
*/
static void ReadHeightmapBMPImageData(byte *map, BmpInfo *info, BmpData *data)
{
uint x, y;
byte gray_palette[256];
if (data->palette != NULL) {
uint i;
bool all_gray = true;
if (info->palette_size != 2) {
for (i = 0; i < info->palette_size && (info->palette_size != 16 || all_gray); i++) {
all_gray &= data->palette[i].r == data->palette[i].g && data->palette[i].r == data->palette[i].b;
gray_palette[i] = RGBToGrayscale(data->palette[i].r, data->palette[i].g, data->palette[i].b);
}
/**
* For a non-gray palette of size 16 we assume that
* the order of the palette determines the height;
* the first entry is the sea (level 0), the second one
* level 1, etc.
*/
if (info->palette_size == 16 && !all_gray) {
for (i = 0; i < info->palette_size; i++) {
gray_palette[i] = 256 * i / info->palette_size;
}
}
} else {
/**
* For a palette of size 2 we assume that the order of the palette determines the height;
* the first entry is the sea (level 0), the second one is the land (level 1)
*/
gray_palette[0] = 0;
gray_palette[1] = 16;
}
}
/* Read the raw image data and convert in 8-bit grayscale */
for (y = 0; y < info->height; y++) {
byte *pixel = &map[y * info->width];
byte *bitmap = &data->bitmap[y * info->width * (info->bpp == 24 ? 3 : 1)];
for (x = 0; x < info->width; x++) {
if (info->bpp != 24) {
*pixel++ = gray_palette[*bitmap++];
} else {
*pixel++ = RGBToGrayscale(*bitmap, *(bitmap + 1), *(bitmap + 2));
bitmap += 3;
}
}
}
}
uint8_t PixelToGrayscale(const pixel_t pixel) {
return RGBToGrayscale(PixelToRGB(pixel));
}
