public: move atlas packing code from renderer, add tests

public/atlas.c

@@ -0,0 +1,62 @@
+/*
+atlas.c - generic 2D atlas packer (strip-based)
+Copyright (C) 1997 id Software
+Copyright (C) Xash3D and Xash3D FWGS developers
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+*/
+#include "atlas.h"
+
+qboolean Atlas_AllocBlock( atlas_t *atlas, int w, int h, int *x, int *y )
+{
+	int i, j;
+	int best, best2;
+	int size = atlas->size;
+
+	best = size;
+
+	for( i = 0; i <= size - w; )
+	{
+		best2 = 0;
+
+		for( j = 0; j < w; j++ )
+		{
+			if( atlas->allocated[i + j] >= best )
+				break;
+			if( atlas->allocated[i + j] > best2 )
+				best2 = atlas->allocated[i + j];
+		}
+
+		if( j == w )
+		{
+			*x = i;
+			*y = best = best2;
+			if( best == 0 )
+				break;
+			i++;
+		}
+		else
+		{
+			i += j + 1;
+		}
+	}
+
+	if( best + h > size )
+		return false;
+
+	for( i = 0; i < w; i++ )
+		atlas->allocated[*x + i] = best + h;
+
+	if( best + h > atlas->max_height )
+		atlas->max_height = best + h;
+
+	return true;
+}