allow querying the bitmap texture underlying a 'Texture' object (if any)

include/mitsuba/render/texture.h

@@ -74,6 +74,9 @@ public:
 	/// Serialize to a binary data stream
 	virtual void serialize(Stream *stream, InstanceManager *manager) const;
 
+	/// Return the underlying bitmap representation (if any)
+	virtual ref<Bitmap> getBitmap() const;
+
 	MTS_DECLARE_CLASS()
 protected:
 	Texture(const Properties &props);

src/librender/texture.cpp

@@ -47,6 +47,7 @@ Spectrum Texture::getMinimum() const { NotImplementedError("getMinimum"); }
 Spectrum Texture::getMaximum() const { NotImplementedError("getMaximum"); }
 bool Texture::isConstant() const { NotImplementedError("isConstant"); }
 bool Texture::usesRayDifferentials() const { NotImplementedError("usesRayDifferentials"); }
+ref<Bitmap> Texture::getBitmap() const { return NULL; }
 
 ref<Texture> Texture::expand() {
 	return this;

src/textures/bitmap.cpp

@@ -400,6 +400,10 @@ public:
 		return result;
 	}
 
+	ref<Bitmap> getBitmap() const {
+		return m_mipmap1.get() ? m_mipmap1->toBitmap() : m_mipmap3->toBitmap();
+	}
+
 	Spectrum eval(const Point2 &uv, const Vector2 &d0, const Vector2 &d1) const {
 		stats::filteredLookups.incrementBase();
 		++stats::filteredLookups;