DDS Loader

dds_loader.cpp

struct DDSHeader {
	uint32_t h3[3];
	int h, w;
	uint32_t h2[2];
	int mipCnt;
	uint32_t h13[13];
	uint32_t fourcc, bitsPerPixel, rMask, gMask, bMask, aMask, caps1, caps2;
	bool IsCubeMap() const { return caps2 == 0xFE00; }
	int GetArraySize() const { return IsCubeMap() ? 6 : 1; }
	int GetMipCnt() const { return std::max(mipCnt, 1); }
};

static void ArrangeRawDDS(void* img, int size)
{
	const DDSHeader* hdr = (DDSHeader*)img;
	DWORD rShift, gShift, bShift, aShift;
	_BitScanForward(&rShift, hdr->rMask);
	_BitScanForward(&gShift, hdr->gMask);
	_BitScanForward(&bShift, hdr->bMask);
	_BitScanForward(&aShift, hdr->aMask);
	std::for_each((uint32_t*)img + 128 / 4, (uint32_t*)img + size / 4, [&](uint32_t& im) {
		im = ((hdr->aMask & im) >> aShift << 24) + ((hdr->bMask & im) >> bShift << 16) + ((hdr->gMask & im) >> gShift << 8) + ((hdr->rMask & im) >> rShift);
	} );
}

static ComPtr<ID3D11ShaderResourceView> LoadDDSTexture(const char* name, ivec2& texSize)
{
	int size;
	ComPtr<ID3D11ShaderResourceView> srv;
	void* img = LoadFile(name, &size);
	if (!img) {
		aflog("LoadDDSTexture failed! %s", name);
		return 0;
	}
	const DDSHeader* hdr = (DDSHeader*)img;

	DXGI_FORMAT format;
	int (*pitchCalcurator)(int, int) = nullptr;
	switch (hdr->fourcc) {
	case 0x31545844: //'1TXD':
		format = DXGI_FORMAT_BC1_UNORM;
		pitchCalcurator = [](int w, int h) { return ((w + 3) / 4) * ((h + 3) / 4) * 8; };
		break;
	case 0x33545844: //'3TXD':
		format = DXGI_FORMAT_BC2_UNORM;
		pitchCalcurator = [](int w, int h) { return ((w + 3) / 4) * ((h + 3) / 4) * 16; };
		break;
	case 0x35545844: //'5TXD':
		format = DXGI_FORMAT_BC3_UNORM;
		pitchCalcurator = [](int w, int h) { return ((w + 3) / 4) * ((h + 3) / 4) * 16; };
		break;
	default:
		ArrangeRawDDS(img, size);
		format = DXGI_FORMAT_R8G8B8A8_UNORM;
		pitchCalcurator = [](int w, int h) { return w * h * 4; };
		break;
	}
	texSize.x = hdr->w;
	texSize.y = hdr->h;

	int arraySize = hdr->GetArraySize();
	int mipCnt = hdr->GetMipCnt();
	CD3D11_TEXTURE2D_DESC desc(format, hdr->w, hdr->h, arraySize, hdr->GetMipCnt(), D3D11_BIND_SHADER_RESOURCE, D3D11_USAGE_DEFAULT, 0, 1, 0, hdr->IsCubeMap() ? D3D11_RESOURCE_MISC_TEXTURECUBE : 0);
	CD3D11_SHADER_RESOURCE_VIEW_DESC srvDesc(hdr->IsCubeMap() ? D3D_SRV_DIMENSION_TEXTURECUBE : D3D_SRV_DIMENSION_TEXTURE2D, desc.Format, 0, -1);
	std::vector<D3D11_SUBRESOURCE_DATA> r;
	int offset = 128;
	for (int a = 0; a < arraySize; a++) {
		for (int m = 0; m < mipCnt; m++) {
			int w = std::max(1, hdr->w >> m);
			int h = std::max(1, hdr->h >> m);
			r.push_back({ (char*)img + offset, (uint32_t)pitchCalcurator(w, 1), 0 });
			offset += pitchCalcurator(w, h);
		}
	}
	ComPtr<ID3D11Texture2D> tex;
	deviceMan11.GetDevice()->CreateTexture2D(&desc, &r[0], &tex);
	deviceMan11.GetDevice()->CreateShaderResourceView(tex.Get(), &srvDesc, &srv);

	free(img);
	return srv;
}