Add KTX and ETC1 texture support

[xonotic/netradiant.git] / libs / etclib.c

diff --git a/libs/etclib.c b/libs/etclib.c
new file mode 100644 (file)
index 0000000..09a149e
--- /dev/null
+++ b/libs/etclib.c
@@ -0,0 +1,114 @@
+// Copyright 2009 Google Inc.
+//
+// Based on the code from Android ETC1Util.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "etclib.h"
+
+static void ETC_DecodeETC1SubBlock( byte *out, qboolean outRGBA, int r, int g, int b, int tableIndex, unsigned int low, qboolean second, qboolean flipped ){
+       int baseX = 0, baseY = 0;
+       const int modifierTable[] = {
+               2, 8, -2, -8,
+               5, 17, -5, -17,
+               9, 29, -9, -29,
+               13, 42, -13, -42,
+               18, 60, -18, -60,
+               24, 80, -24, -80,
+               33, 106, -33, -106,
+               47, 183, -47, -183
+       };
+       const int *table = modifierTable + tableIndex * 4;
+       int i;  
+
+       if ( second ) {
+               if ( flipped ) {
+                       baseY = 2;
+               }
+               else {
+                       baseX = 2;
+               }
+       }
+
+       for ( i = 0; i < 8; i++ )
+       {
+               int x, y, k, delta;
+               int qr, qg, qb;
+               byte *q;
+
+               if ( flipped ) {
+                       x = baseX + ( i >> 1 );
+                       y = baseY + ( i & 1 );
+               }
+               else {
+                       x = baseX + ( i >> 2 );
+                       y = baseY + ( i & 3 );
+               }
+               k = y + ( x * 4 );
+               delta = table[( ( low >> k ) & 1 ) | ( ( low >> ( k + 15 ) ) & 2 )];
+
+               qr = r + delta;
+               qg = g + delta;
+               qb = b + delta;
+               if ( outRGBA ) {
+                       q = out + 4 * ( x + 4 * y );
+               }
+               else {
+                       q = out + 3 * ( x + 4 * y );
+               }
+               *( q++ ) = ( ( qr > 0 ) ? ( ( qr < 255 ) ? qr : 255 ) : 0 );
+               *( q++ ) = ( ( qg > 0 ) ? ( ( qg < 255 ) ? qg : 255 ) : 0 );
+               *( q++ ) = ( ( qb > 0 ) ? ( ( qb < 255 ) ? qb : 255 ) : 0 );
+               if ( outRGBA ) {
+                       *( q++ ) = 255;
+               }
+       }
+}
+
+void ETC_DecodeETC1Block( const byte* in, byte* out, qboolean outRGBA ){
+       unsigned int high = ( in[0] << 24 ) | ( in[1] << 16 ) | ( in[2] << 8 ) | in[3];
+       unsigned int low = ( in[4] << 24 ) | ( in[5] << 16 ) | ( in[6] << 8 ) | in[7];
+       int r1, r2, g1, g2, b1, b2;
+       qboolean flipped = ( ( high & 1 ) != 0 );
+
+       if ( high & 2 ) {
+               int rBase, gBase, bBase;
+               const int lookup[] = { 0, 1, 2, 3, -4, -3, -2, -1 };
+
+               rBase = ( high >> 27 ) & 31;
+               r1 = ( rBase << 3 ) | ( rBase >> 2 );
+               rBase = ( rBase + ( lookup[( high >> 24 ) & 7] ) ) & 31;
+               r2 = ( rBase << 3 ) | ( rBase >> 2 );
+
+               gBase = ( high >> 19 ) & 31;
+               g1 = ( gBase << 3 ) | ( gBase >> 2 );
+               gBase = ( gBase + ( lookup[( high >> 16 ) & 7] ) ) & 31;
+               g2 = ( gBase << 3 ) | ( gBase >> 2 );
+
+               bBase = ( high >> 11 ) & 31;
+               b1 = ( bBase << 3 ) | ( bBase >> 2 );
+               bBase = ( bBase + ( lookup[( high >> 8 ) & 7] ) ) & 31;
+               b2 = ( bBase << 3 ) | ( bBase >> 2 );
+       }
+       else {
+               r1 = ( ( high >> 24 ) & 0xf0 ) | ( ( high >> 28 ) & 0xf );
+               r2 = ( ( high >> 20 ) & 0xf0 ) | ( ( high >> 24 ) & 0xf );
+               g1 = ( ( high >> 16 ) & 0xf0 ) | ( ( high >> 20 ) & 0xf );
+               g2 = ( ( high >> 12 ) & 0xf0 ) | ( ( high >> 16 ) & 0xf );
+               b1 = ( ( high >> 8 ) & 0xf0 ) | ( ( high >> 12 ) & 0xf );
+               b2 = ( ( high >> 4 ) & 0xf0 ) | ( ( high >> 8 ) & 0xf );
+       }
+
+       ETC_DecodeETC1SubBlock( out, outRGBA, r1, g1, b1, ( high >> 5 ) & 7, low, qfalse, flipped );
+       ETC_DecodeETC1SubBlock( out, outRGBA, r2, g2, b2, ( high >> 2 ) & 7, low, qtrue, flipped );
+}