Functions to rasterize textures to bitmaps

include/mitsuba/hw/basicshader.h

@@ -75,6 +75,8 @@ public:
 
 	Shader *createShader(Renderer *renderer) const;
 
+	ref<Bitmap> getBitmap(const Vector2i &resolutionHint) const;
+
 	void serialize(Stream *stream, InstanceManager *manager) const;
 
 	MTS_DECLARE_CLASS()
@@ -128,6 +130,8 @@ public:
 
 	Shader *createShader(Renderer *renderer) const;
 
+	ref<Bitmap> getBitmap(const Vector2i &resolutionHint) const;
+
 	void serialize(Stream *stream, InstanceManager *manager) const;
 
 	MTS_DECLARE_CLASS()
@@ -185,6 +189,8 @@ public:
 
 	Shader *createShader(Renderer *renderer) const;
 
+	ref<Bitmap> getBitmap(const Vector2i &resolutionHint) const;
+
 	void serialize(Stream *stream, InstanceManager *manager) const;
 
 	MTS_DECLARE_CLASS()
@@ -242,6 +248,8 @@ public:
 
 	Shader *createShader(Renderer *renderer) const;
 
+	ref<Bitmap> getBitmap(const Vector2i &resolutionHint) const;
+
 	void serialize(Stream *stream, InstanceManager *manager) const;
 
 	MTS_DECLARE_CLASS()
@@ -302,6 +310,8 @@ public:
 
 	void serialize(Stream *stream, InstanceManager *manager) const;
 
+	ref<Bitmap> getBitmap(const Vector2i &resolutionHint) const;
+
 	MTS_DECLARE_CLASS()
 protected:
 	ref<const Texture> m_a, m_b;

include/mitsuba/render/texture.h

@@ -74,8 +74,17 @@ 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;
+	 * \brief Return a bitmap representation of the texture
+	 *
+	 * When the class implementing this interface is a bitmap-backed texture,
+	 * this function directly returns the underlying bitmap. When it is procedural,
+	 * a bitmap version must first be generated. In this case, the parameter
+	 * \ref resolutionHint is used to control the target resolution. The default
+	 * value <tt>-1, -1</tt> allows the implementation to choose a suitable
+	 * resolution by itself.
+	 */
+	virtual ref<Bitmap> getBitmap(const Vector2i &resolutionHint = Vector2i(-1, -1)) const;
 
 	MTS_DECLARE_CLASS()
 protected:
@@ -109,6 +118,18 @@ public:
 	virtual Spectrum eval(const Point2 &uv, const Vector2 &d0,
 			const Vector2 &d1) const = 0;
 
+	/**
+	 * \brief Return a bitmap representation of the texture
+	 *
+	 * When the class implementing this interface is a bitmap-backed texture,
+	 * this function directly returns the underlying bitmap. When it is procedural,
+	 * a bitmap version must first be generated. In this case, the parameter
+	 * \ref resolutionHint is used to control the target resolution. The default
+	 * value <tt>-1, -1</tt> allows the implementation to choose a suitable
+	 * resolution by itself.
+	 */
+	virtual ref<Bitmap> getBitmap(const Vector2i &resolutionHint = Vector2i(-1, -1)) const;
+
 	MTS_DECLARE_CLASS()
 protected:
 	Texture2D(const Properties &props);

src/libhw/basicshader.cpp

@@ -20,6 +20,7 @@
 
 MTS_NAMESPACE_BEGIN
 
+
 ConstantSpectrumTexture::ConstantSpectrumTexture(Stream *stream, InstanceManager *manager)
  : Texture(stream, manager) {
 	m_value = Spectrum(stream);
@@ -31,6 +32,12 @@ void ConstantSpectrumTexture::serialize(Stream *stream, InstanceManager *manager
 	m_value.serialize(stream);
 }
 
+ref<Bitmap> ConstantSpectrumTexture::getBitmap(const Vector2i &resolutionHint) const {
+	ref<Bitmap> result = new Bitmap(Bitmap::ESpectrum, Bitmap::EFloat, Vector2i(1, 1));
+	*((Spectrum *) result->getFloatData()) = m_value;
+	return result;
+}
+
 ConstantFloatTexture::ConstantFloatTexture(Stream *stream, InstanceManager *manager)
  : Texture(stream, manager) {
 	m_value = stream->readFloat();
@@ -41,6 +48,12 @@ void ConstantFloatTexture::serialize(Stream *stream, InstanceManager *manager) c
 	stream->writeFloat(m_value);
 }
 
+ref<Bitmap> ConstantFloatTexture::getBitmap(const Vector2i &resolutionHint) const {
+	ref<Bitmap> result = new Bitmap(Bitmap::ELuminance, Bitmap::EFloat, Vector2i(1, 1));
+	*result->getFloatData() = m_value;
+	return result;
+}
+
 SpectrumProductTexture::SpectrumProductTexture(Stream *stream, InstanceManager *manager)
  : Texture(stream, manager) {
 	m_a = static_cast<Texture *>(manager->getInstance(stream));
@@ -53,6 +66,12 @@ void SpectrumProductTexture::serialize(Stream *stream, InstanceManager *manager)
 	manager->serialize(stream, m_b.get());
 }
 
+ref<Bitmap> SpectrumProductTexture::getBitmap(const Vector2i &resolutionHint) const {
+	ref<Bitmap> bitmap1 = m_a->getBitmap(resolutionHint);
+	ref<Bitmap> bitmap2 = m_b->getBitmap(resolutionHint);
+	return Bitmap::arithmeticOperation(Bitmap::EMultiplication, bitmap1.get(), bitmap2.get());
+}
+
 SpectrumAdditionTexture::SpectrumAdditionTexture(Stream *stream, InstanceManager *manager)
  : Texture(stream, manager) {
 	m_a = static_cast<Texture *>(manager->getInstance(stream));
@@ -65,6 +84,12 @@ void SpectrumAdditionTexture::serialize(Stream *stream, InstanceManager *manager
 	manager->serialize(stream, m_b.get());
 }
 
+ref<Bitmap> SpectrumAdditionTexture::getBitmap(const Vector2i &resolutionHint) const {
+	ref<Bitmap> bitmap1 = m_a->getBitmap(resolutionHint);
+	ref<Bitmap> bitmap2 = m_b->getBitmap(resolutionHint);
+	return Bitmap::arithmeticOperation(Bitmap::EAddition, bitmap1.get(), bitmap2.get());
+}
+
 SpectrumSubtractionTexture::SpectrumSubtractionTexture(Stream *stream, InstanceManager *manager)
  : Texture(stream, manager) {
 	m_a = static_cast<Texture *>(manager->getInstance(stream));
@@ -77,6 +102,12 @@ void SpectrumSubtractionTexture::serialize(Stream *stream, InstanceManager *mana
 	manager->serialize(stream, m_b.get());
 }
 
+ref<Bitmap> SpectrumSubtractionTexture::getBitmap(const Vector2i &resolutionHint) const {
+	ref<Bitmap> bitmap1 = m_a->getBitmap(resolutionHint);
+	ref<Bitmap> bitmap2 = m_b->getBitmap(resolutionHint);
+	return Bitmap::arithmeticOperation(Bitmap::ESubtraction, bitmap1.get(), bitmap2.get());
+}
+
 class ConstantSpectrumTextureShader : public Shader {
 public:
 	ConstantSpectrumTextureShader(Renderer *renderer, const Spectrum &value)

src/librender/texture.cpp

@@ -47,7 +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<Bitmap> Texture::getBitmap(const Vector2i &) const { NotImplementedError("getBitmap"); }
 
 ref<Texture> Texture::expand() {
 	return this;
@@ -100,6 +100,22 @@ Spectrum Texture2D::eval(const Intersection &its, bool filter) const {
 		return eval(uv);
 	}
 }
+
+ref<Bitmap> Texture2D::getBitmap(const Vector2i &resolutionHint) const {
+	Vector2i res(resolutionHint);
+	if (res.x <= 0 || res.y <= 0)
+		res = Vector2i(32);
+
+	Float invX = 1.0f / res.x, invY = 1.0f / res.y;
+
+	ref<Bitmap> bitmap = new Bitmap(Bitmap::ESpectrum, Bitmap::EFloat, res);
+	Spectrum *target = (Spectrum *) bitmap->getFloatData();
+	for (int y=0; y<res.y; ++y)
+		for (int x=0; x<res.x; ++x)
+			*target++ = eval(Point2((x + 0.5f) * invX, (y + 0.5f) * invY));
+	return bitmap;
+}
+
 MTS_IMPLEMENT_CLASS(Texture, true, ConfigurableObject)
 MTS_IMPLEMENT_CLASS(Texture2D, true, Texture)
 MTS_NAMESPACE_END

src/textures/bitmap.cpp

@@ -428,7 +428,7 @@ public:
 		return result;
 	}
 
-	ref<Bitmap> getBitmap() const {
+	ref<Bitmap> getBitmap(const Vector2i &/* unused */) {
 		return m_mipmap1.get() ? m_mipmap1->toBitmap() : m_mipmap3->toBitmap();
 	}