added a new Texture::isMonochromatic function

include/mitsuba/hw/basicshader.h

@@ -73,6 +73,10 @@ public:
 		return false;
 	}
 
+	inline bool isMonochromatic() const {
+		return m_value == Spectrum(m_value[0]);
+	}
+
 	Shader *createShader(Renderer *renderer) const;
 
 	ref<Bitmap> getBitmap(const Vector2i &resolutionHint) const;
@@ -128,6 +132,10 @@ public:
 		return false;
 	}
 
+	inline bool isMonochromatic() const {
+		return true;
+	}
+
 	Shader *createShader(Renderer *renderer) const;
 
 	ref<Bitmap> getBitmap(const Vector2i &resolutionHint) const;
@@ -187,6 +195,10 @@ public:
 		return m_a->usesRayDifferentials() || m_b->usesRayDifferentials();
 	}
 
+	inline bool isMonochromatic() const {
+		return m_a->isMonochromatic() && m_b->isMonochromatic();
+	}
+
 	Shader *createShader(Renderer *renderer) const;
 
 	ref<Bitmap> getBitmap(const Vector2i &resolutionHint) const;
@@ -246,6 +258,10 @@ public:
 		return m_a->usesRayDifferentials() || m_b->usesRayDifferentials();
 	}
 
+	inline bool isMonochromatic() const {
+		return m_a->isMonochromatic() && m_b->isMonochromatic();
+	}
+
 	Shader *createShader(Renderer *renderer) const;
 
 	ref<Bitmap> getBitmap(const Vector2i &resolutionHint) const;
@@ -306,6 +322,10 @@ public:
 		return m_a->usesRayDifferentials() || m_b->usesRayDifferentials();
 	}
 
+	inline bool isMonochromatic() const {
+		return m_a->isMonochromatic() && m_b->isMonochromatic();
+	}
+
 	Shader *createShader(Renderer *renderer) const;
 
 	void serialize(Stream *stream, InstanceManager *manager) const;

include/mitsuba/render/texture.h

@@ -63,9 +63,16 @@ public:
 	/// Return the resolution in pixels, if applicable
 	virtual Vector3i getResolution() const;
 
-	/// Return whether the texture takes on a single constant value
+	/// Return whether the texture takes on a constant value everywhere
 	virtual bool isConstant() const;
 
+	/**
+	 * \brief Return whether the texture is monochromatic / spectrally uniform
+	 *
+	 * The implementation may conservatively return \c false if it is not sure.
+	 */
+	virtual bool isMonochromatic() const;
+
 	/**
 	 * \brief Does this texture perform any pre-filtering when
 	 * ray differentials are available?

src/libpython/render.cpp

@@ -482,6 +482,7 @@ void export_render() {
 		.def("getSensor", shape_getSensor, BP_RETURN_VALUE)
 		.def("hasBSDF", &Shape::hasBSDF)
 		.def("getBSDF", shape_getBSDF, BP_RETURN_VALUE)
+		.def("setBSDF", &Shape::setBSDF)
 		.def("getPrimitiveCount", &Shape::getPrimitiveCount)
 		.def("getEffectivePrimitiveCount", &Shape::getEffectivePrimitiveCount)
 		.def("copyAttachments", &Shape::copyAttachments);

src/librender/texture.cpp

@@ -46,6 +46,7 @@ Spectrum Texture::getAverage() const { NotImplementedError("getAverage"); }
 Spectrum Texture::getMinimum() const { NotImplementedError("getMinimum"); }
 Spectrum Texture::getMaximum() const { NotImplementedError("getMaximum"); }
 bool Texture::isConstant() const { NotImplementedError("isConstant"); }
+bool Texture::isMonochromatic() const { NotImplementedError("isMonochromatic"); }
 bool Texture::usesRayDifferentials() const { NotImplementedError("usesRayDifferentials"); }
 ref<Bitmap> Texture::getBitmap(const Vector2i &) const { NotImplementedError("getBitmap"); }
 

src/textures/bitmap.cpp

@@ -542,6 +542,10 @@ public:
 		return true;
 	}
 
+	bool isMonochromatic() const {
+		return m_mipmap1.get() != NULL;
+	}
+
 	Vector3i getResolution() const {
 		if (m_mipmap3.get()) {
 			return Vector3i(

src/textures/checkerboard.cpp

@@ -105,6 +105,11 @@ public:
 		return false;
 	}
 
+	bool isMonochromatic() const {
+		return Spectrum(m_color0[0]) == m_color0
+			&& Spectrum(m_color1[0]) == m_color1;
+	}
+
 	std::string toString() const {
 		std::ostringstream oss;
 		oss << "Checkerboard[" << endl

src/textures/curvature.cpp

@@ -105,6 +105,10 @@ public:
 		return Spectrum(1.0f);
 	}
 
+	bool isMonochromatic() const {
+		return false;
+	}
+
 	bool isConstant() const {
 		return false;
 	}

src/textures/gridtexture.cpp

@@ -122,6 +122,11 @@ public:
 		return false;
 	}
 
+	bool isMonochromatic() const {
+		return Spectrum(m_color0[0]) == m_color0
+			&& Spectrum(m_color1[0]) == m_color1;
+	}
+
 	std::string toString() const {
 		return "GridTexture[]";
 	}

src/textures/scale.cpp

@@ -138,6 +138,10 @@ public:
 		return m_nested->usesRayDifferentials();
 	}
 
+	bool isMonochromatic() const {
+		return m_nested->isMonochromatic();
+	}
+
 	Shader *createShader(Renderer *renderer) const;
 
 	void serialize(Stream *stream, InstanceManager *manager) const {

src/textures/vertexcolors.cpp

@@ -80,6 +80,10 @@ public:
 		return false;
 	}
 
+	bool isMonochromatic() const {
+		return false; /* No way to tell from here, really .. */
+	}
+
 	std::string toString() const {
 		return "VertexColors[]";
 	}

src/textures/wireframe.cpp

@@ -152,6 +152,11 @@ public:
 		return false;
 	}
 
+	bool isMonochromatic() const {
+		return Spectrum(m_edgeColor[0]) == m_edgeColor
+			&& Spectrum(m_interiorColor[0]) == m_interiorColor;
+	}
+
 	std::string toString() const {
 		std::ostringstream oss;
 		oss << "WireFrame[" << endl