1 files changed, 131 insertions, 0 deletions
diff --git a/core/math/geometry.cpp b/core/math/geometry.cpp
index cb76b9ed0f..2d525dd1ce 100644
--- a/core/math/geometry.cpp
+++ b/core/math/geometry.cpp
@@ -1004,3 +1004,134 @@ DVector<Plane> Geometry::build_capsule_planes(float p_radius, float p_height, in
 
 }
 
+
+struct _AtlasWorkRect {
+
+	Size2i s;
+	Point2i p;
+	int idx;
+	_FORCE_INLINE_ bool operator<(const _AtlasWorkRect& p_r) const { return s.width > p_r.s.width; };
+};
+
+struct _AtlasWorkRectResult {
+
+	Vector<_AtlasWorkRect> result;
+	int max_w;
+	int max_h;
+};
+
+void Geometry::make_atlas(const Vector<Size2i>& p_rects,Vector<Point2i>& r_result, Size2i& r_size) {
+
+	//super simple, almost brute force scanline stacking fitter
+	//it's pretty basic for now, but it tries to make sure that the aspect ratio of the
+	//resulting atlas is somehow square. This is necesary because video cards have limits
+	//on texture size (usually 2048 or 4096), so the more square a texture, the more chances
+	//it will work in every hardware.
+	// for example, it will prioritize a 1024x1024 atlas (works everywhere) instead of a
+	// 256x8192 atlas (won't work anywhere).
+
+	ERR_FAIL_COND(p_rects.size()==0);
+
+	Vector<_AtlasWorkRect> wrects;
+	wrects.resize(p_rects.size());
+	for(int i=0;i<p_rects.size();i++) {
+		wrects[i].s=p_rects[i];
+		wrects[i].idx=i;
+	}
+	wrects.sort();
+	int widest = wrects[0].s.width;
+
+	Vector<_AtlasWorkRectResult> results;
+
+	for(int i=0;i<=12;i++) {
+
+		int w = 1<<i;
+		int max_h=0;
+		int max_w=0;
+		if ( w < widest )
+			continue;
+
+		Vector<int> hmax;
+		hmax.resize(w);
+		for(int j=0;j<w;j++)
+			hmax[j]=0;
+
+		//place them
+		int ofs=0;
+		int limit_h=0;
+		for(int j=0;j<wrects.size();j++) {
+
+
+			if (ofs+wrects[j].s.width > w) {
+
+				ofs=0;
+			}
+
+			int from_y=0;
+			for(int k=0;k<wrects[j].s.width;k++) {
+
+				if (hmax[ofs+k] > from_y)
+					from_y=hmax[ofs+k];
+			}
+
+			wrects[j].p.x=ofs;
+			wrects[j].p.y=from_y;
+			int end_h = from_y+wrects[j].s.height;
+			int end_w = ofs+wrects[j].s.width;
+			if (ofs==0)
+				limit_h=end_h;
+
+			for(int k=0;k<wrects[j].s.width;k++) {
+
+				hmax[ofs+k]=end_h;
+			}
+
+			if (end_h > max_h)
+				max_h=end_h;
+
+			if (end_w > max_w)
+				max_w=end_w;
+
+			if (ofs==0 || end_h>limit_h ) //while h limit not reched, keep stacking
+				ofs+=wrects[j].s.width;
+
+		}
+
+		_AtlasWorkRectResult result;
+		result.result=wrects;
+		result.max_h=max_h;
+		result.max_w=max_w;
+		results.push_back(result);
+
+	}
+
+	//find the result with the best aspect ratio
+
+	int best=-1;
+	float best_aspect=1e20;
+
+	for(int i=0;i<results.size();i++) {
+
+		float h = nearest_power_of_2(results[i].max_h);
+		float w = nearest_power_of_2(results[i].max_w);
+		float aspect = h>w ? h/w : w/h;
+		if (aspect < best_aspect) {
+			best=i;
+			best_aspect=aspect;
+		}
+	}
+
+	r_result.resize(p_rects.size());
+
+	for(int i=0;i<p_rects.size();i++) {
+
+		r_result[ results[best].result[i].idx ]=results[best].result[i].p;
+	}
+
+	r_size=Size2(results[best].max_w,results[best].max_h );
+
+}
+
+
+
+