PNG_TO_DDS_RGBA_EXPORTER.cpp

// PNG_TO_DDS_RGBA_EXPORTER.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

#include <iostream>
#include <fstream>
#include <cinttypes>
#include <vector>

#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"

int main(int argv, char** argc)
{
	if (argv != 3)
	{
		printf("Whoops, make sure you call with two arguments! Like so:\n");
		printf("PNG_TO_DDS_RGBA_EXPORTER.exe input.png output.dds");
		return 1;
	}

	std::string pngFile = argc[1];
	std::string ddsFile = argc[2];

	int w, h, components;
	stbi_uc* bytes = stbi_load(pngFile.c_str(), &w, &h, &components, 4);

	if (bytes == nullptr)
	{
		printf("Couldn't load the input png file, incorrect format?");
	}

	std::ofstream _out(ddsFile, std::ios::binary);

	int _zero = 0x00;
	int const _dataSize = w*h*4;
	
	uint32_t _output[] = {0x7C, 0x02100F, static_cast<uint32_t>(h), static_cast<uint32_t>(w), 0x800, 0x01, 0x01};
	uint32_t _output2[] = {0x20, 0x41, 0x00, 0x20, 0xFF, 0xFF00, 0xFF0000, 0xFF000000, 0x1000};
	
	std::vector<stbi_uc> _imgData;
	_imgData.resize(_dataSize);
	
	memcpy(_imgData.data(), bytes, _dataSize);
	free(bytes);
	
	for (int i = 3; i < _dataSize; i += 4)
	{
		unsigned char const _factor = 2;
		int _value = std::min(_imgData.at(i) * _factor, 255);
	
		_imgData.at(i) = static_cast<unsigned char>(_value);
	}
	
	_out << "DDS ";
	_out.write(reinterpret_cast<char*>(&_output), 4 * 7);
	
	for (int o = 0; o < 11; o++)
		_out.write(reinterpret_cast<char*>(&_zero), 4);
	
	_out.write(reinterpret_cast<char*>(&_output2), 4 * 9);
	
	for (int o = 0; o < 4; o++)
		_out.write(reinterpret_cast<char*>(&_zero), 4);
	
	_out.write(reinterpret_cast<char*>(_imgData.data()), _dataSize);
	_out.close();
}