godot/drivers/squish/image_compress_squish.cpp

/*************************************************************************/
/*  image_compress_squish.cpp                                            */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
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/* Copyright (c) 2007-2016 Juan Linietsky, Ariel Manzur.                 */
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#include "image_compress_squish.h"
#include "squish/squish.h"
#include "print_string.h"

void image_compress_squish(Image *p_image) {

	int w=p_image->get_width();
	int h=p_image->get_height();

	if (p_image->get_mipmaps() == 0) {
		ERR_FAIL_COND( !w || w % 4 != 0);
		ERR_FAIL_COND( !h || h % 4 != 0);
	} else {
		ERR_FAIL_COND( !w || w !=nearest_power_of_2(w) );
		ERR_FAIL_COND( !h || h !=nearest_power_of_2(h) );
	};

	if (p_image->get_format()>=Image::FORMAT_BC1)
		return; //do not compress, already compressed

	int shift=0;
	int squish_comp=squish::kColourRangeFit;
	Image::Format target_format;

	if (p_image->get_format()==Image::FORMAT_GRAYSCALE_ALPHA) {
		//compressed normalmap
		target_format = Image::FORMAT_BC3; squish_comp|=squish::kDxt5;;
	} else if (p_image->detect_alpha()!=Image::ALPHA_NONE) {

		target_format = Image::FORMAT_BC2; squish_comp|=squish::kDxt3;;
	} else {
		target_format = Image::FORMAT_BC1; shift=1; squish_comp|=squish::kDxt1;;
	}

	p_image->convert(Image::FORMAT_RGBA); //always expects rgba

	int mm_count = p_image->get_mipmaps();

	DVector<uint8_t> data;
	int target_size = Image::get_image_data_size(w,h,target_format,mm_count);
	data.resize(target_size);

	DVector<uint8_t>::Read rb = p_image->get_data().read();
	DVector<uint8_t>::Write wb = data.write();

	int dst_ofs=0;

	for(int i=0;i<=mm_count;i++) {

		int src_ofs = p_image->get_mipmap_offset(i);
		squish::CompressImage( &rb[src_ofs],w,h,&wb[dst_ofs],squish_comp);
		dst_ofs+=(MAX(4,w)*MAX(4,h))>>shift;
		w>>=1;
		h>>=1;
	}

	rb = DVector<uint8_t>::Read();
	wb = DVector<uint8_t>::Write();

	p_image->create(p_image->get_width(),p_image->get_height(),p_image->get_mipmaps(),target_format,data);

}