#define STB_IMAGE_IMPLEMENTATION
#include"stb_image.h"
#include "image.h"

Image::Image(const int& width, const int& height, RGBA* data) {
	m_width = width;
	m_height = height;
	if (data) {
		m_data = new RGBA[m_width * m_height];
		memcpy(m_data, data, sizeof(RGBA) * m_width * m_height);
	}
}

Image::~Image() {
	if (m_data != nullptr) {
		delete[] m_data;
	}
}

//仅接收（-1，1）的参数
RGBA Image::GetColor(const float& p_u, const float& p_v)
{
	if (!m_data) { return RGBA(255,255,255,255); }
	/*此处注意截断误差，不要直接算index，一定要让x和y分别截断一下*/
	int x = fmod(p_u + 1, 1.f) * m_width;
	int y = fmod(p_v + 1, 1.f) * m_height;
	return m_data[x + y * m_width];
}

Image* Image::CreateImage(const std::string& path) {
	int picType = 0;
	int width{ 0 }, height{ 0 };

	stbi_set_flip_vertically_on_load(true);

	unsigned char* bits = stbi_load(path.c_str(), &width, &height, &picType, STBI_rgb_alpha);
	for (int i = 0; i < width * height * 4; i += 4)
	{
		BYTE tmp = bits[i];
		bits[i] = bits[i + 2];
		bits[i + 2] = tmp;
	}

	Image* image = new Image(width, height, (RGBA*)bits);

	stbi_image_free(bits);

	return image;

}

void Image::DestroyImage(Image* image) {
	if (image) {
		delete image;
	}
}