Function unpack_bc4

engine/dlib/src/basis/encoder/basisu_gpu_texture.cpp:336–354

	};

	void unpack_bc4(const void *pBlock_bits, uint8_t *pPixels, uint32_t stride)
	{
		static_assert(sizeof(bc4_block) == 8, "sizeof(bc4_block) == 8");

		const bc4_block *pBlock = static_cast<const bc4_block *>(pBlock_bits);

		uint8_t sel_values[8];
		bc4_block::get_block_values(sel_values, pBlock->get_low_alpha(), pBlock->get_high_alpha());

		const uint64_t selector_bits = pBlock->get_selector_bits();

		for (uint32_t y = 0; y < 4; y++, pPixels += (stride * 4U))
		{
			pPixels[0] = sel_values[pBlock->get_selector(0, y, selector_bits)];
			pPixels[stride * 1] = sel_values[pBlock->get_selector(1, y, selector_bits)];
			pPixels[stride * 2] = sel_values[pBlock->get_selector(2, y, selector_bits)];
			pPixels[stride * 3] = sel_values[pBlock->get_selector(3, y, selector_bits)];
		}
	}
	
	// Returns false if the block uses 3-color punchthrough alpha mode, which isn't supported on some GPU's for BC3.
	bool unpack_bc3(const void *pBlock_bits, color_rgba *pPixels)