From: Mikko Rasa <tdb@tdb.fi>
Date: Wed, 22 May 2013 20:03:07 +0000 (+0300)
Subject: Make CompositeShape::get_intersections work with null points
X-Git-Url: http://git.tdb.fi/?a=commitdiff_plain;h=39626a640e3b6a1ff8894e0cf47db68540d669b2;p=libs%2Fmath.git

Make CompositeShape::get_intersections work with null points

This was a bit tricky, since it's necessary to inspect the points returned
by component shapes to see if they're actually on the composite surface.
To that end, a temporary buffer is allocated.  This is most likely used in
interactive point-and-pick situations, so the performance loss should not
be significant.
---

diff --git a/source/geometry/compositeshape.h b/source/geometry/compositeshape.h
index 55467d7..f0b1f52 100644
--- a/source/geometry/compositeshape.h
+++ b/source/geometry/compositeshape.h
@@ -1,6 +1,7 @@
 #ifndef MSP_GEOMETRY_COMPOSITESHAPE_H_
 #define MSP_GEOMETRY_COMPOSITESHAPE_H_
 
+#include <algorithm>
 #include <stdexcept>
 #include <vector>
 #include "shape.h"
@@ -19,11 +20,16 @@ protected:
 	typedef std::vector<Shape<T, D> *> ShapeArray;
 
 	ShapeArray shapes;
+	unsigned max_isect;
+	unsigned min_scratch;
 
 	CompositeShape() { }
 	CompositeShape(const Shape<T, D> &, const Shape<T, D> &);
 	template<typename Iter>
 	void init_from_iter_range(const Iter &, const Iter &);
+private:
+	void init();
+protected:
 	CompositeShape(const CompositeShape &);
 	CompositeShape &operator=(const CompositeShape &);
 public:
@@ -31,7 +37,7 @@ public:
 
 	virtual BoundingBox<T, D> get_axis_aligned_bounding_box() const;
 	virtual bool contains(const LinAl::Vector<T, D> &) const;
-	virtual unsigned get_max_ray_intersections() const;
+	virtual unsigned get_max_ray_intersections() const { return max_isect; }
 	virtual unsigned get_intersections(const Ray<T, D> &, SurfacePoint<T, D> *, unsigned) const;
 };
 
@@ -41,6 +47,7 @@ inline CompositeShape<T, D, O>::CompositeShape(const Shape<T, D> &s1, const Shap
 	shapes.reserve(2);
 	shapes.push_back(s1.clone());
 	shapes.push_back(s2.clone());
+	init();
 }
 
 template<typename T, unsigned D, typename O>
@@ -52,11 +59,27 @@ inline void CompositeShape<T, D, O>::init_from_iter_range(const Iter &begin, con
 
 	for(Iter i=begin; i!=end; ++i)
 		shapes.push_back((*i)->clone());
+	init();
+}
+
+template<typename T, unsigned D, typename O>
+inline void CompositeShape<T, D, O>::init()
+{
+	max_isect = 0;
+	min_scratch = 0;
+	for(typename ShapeArray::const_iterator i=shapes.begin(); i!=shapes.end(); ++i)
+	{
+		unsigned mi = (*i)->get_max_ray_intersections();
+		max_isect += mi;
+		min_scratch = std::max(min_scratch, mi);
+	}
 }
 
 template<typename T, unsigned D, typename O>
 inline CompositeShape<T, D, O>::CompositeShape(const CompositeShape<T, D, O> &other):
-	shapes(other.shapes)
+	shapes(other.shapes),
+	max_isect(other.max_isect),
+	min_scratch(other.min_scratch)
 {
 	for(typename ShapeArray::iterator i=shapes.begin(); i!=shapes.end(); ++i)
 		*i = (*i)->clone();
@@ -71,6 +94,9 @@ inline CompositeShape<T, D, O> &CompositeShape<T, D, O>::operator=(const Composi
 	shapes = other.shapes;
 	for(typename ShapeArray::iterator i=shapes.begin(); i!=shapes.end(); ++i)
 		*i = (*i)->clone();
+
+	max_isect = other.max_isect;
+	min_scratch = other.min_scratch;
 }
 
 template<typename T, unsigned D, typename O>
@@ -107,26 +133,25 @@ inline bool CompositeShape<T, D, O>::contains(const LinAl::Vector<T, D> &point)
 	return inside;
 }
 
-template<typename T, unsigned D, typename O>
-inline unsigned CompositeShape<T, D, O>::get_max_ray_intersections() const
-{
-	unsigned max_isect = 0;
-	for(typename ShapeArray::const_iterator i=shapes.begin(); i!=shapes.end(); ++i)
-		max_isect += (*i)->get_max_ray_intersections();
-	return max_isect;
-}
-
 template<typename T, unsigned D, typename O>
 inline unsigned CompositeShape<T, D, O>::get_intersections(const Ray<T, D> &ray, SurfacePoint<T, D> *points, unsigned size) const
 {
+	SurfacePoint<T, D> *buffer = points;
+	unsigned buf_size = size;
+	if(!points)
+	{
+		buffer = new SurfacePoint<T, D>[min_scratch];
+		buf_size = min_scratch;
+	}
+
 	unsigned n = 0;
 	for(typename ShapeArray::const_iterator i=shapes.begin(); (n<size && i!=shapes.end()); ++i)
 	{
-		unsigned base = n;
-		unsigned count = (*i)->get_intersections(ray, points+base, size-base);
+		unsigned base = (points ? n : 0);
+		unsigned count = (*i)->get_intersections(ray, buffer+base, buf_size-base);
 		for(unsigned j=0; (n<size && j<count); ++j)
 		{
-			SurfacePoint<T, D> &pt = points[base+j];
+			SurfacePoint<T, D> &pt = buffer[base+j];
 
 			bool surface = Ops::init_surface();
 			for(typename ShapeArray::const_iterator k=shapes.begin(); k!=shapes.end(); ++k)
@@ -143,7 +168,10 @@ inline unsigned CompositeShape<T, D, O>::get_intersections(const Ray<T, D> &ray,
 		}
 	}
 
-	sort_points(points, n);
+	if(points)
+		sort_points(points, n);
+	else
+		delete[] buffer;
 
 	return n;
 }