added support for wireframe rendering

include/mitsuba/render/shape.h

@@ -171,7 +171,10 @@ public:
 	const Shape *shape;
 
 	/// Have texture coordinate partials been computed
-	bool hasUVPartials;
+	bool hasUVPartials : 1;
+
+	/// Primitive index, e.g. the triangle ID (if applicable)
+	uint32_t primIndex : 31;
 };
 
 /** \brief Abstract base class of all shapes

include/mitsuba/render/skdtree.h

@@ -425,6 +425,7 @@ protected:
 			its.wi = its.toLocal(-ray.d);
 			its.shape = trimesh;
 			its.hasUVPartials = false;
+			its.primIndex = cache->primIndex;
 		} else {
 			shape->fillIntersectionRecord(ray, 
 				reinterpret_cast<const uint8_t*>(temp) + 8, its);

src/textures/SConscript

@@ -5,5 +5,6 @@ plugins += env.SharedLibrary('scale', ['scale.cpp'])
 plugins += env.SharedLibrary('gridtexture', ['gridtexture.cpp'])
 plugins += env.SharedLibrary('checkerboard', ['checkerboard.cpp'])
 plugins += env.SharedLibrary('vertexcolors', ['vertexcolors.cpp'])
+plugins += env.SharedLibrary('wireframe', ['wireframe.cpp'])
 
 Export('plugins')

src/textures/wireframe.cpp

@@ -0,0 +1,169 @@
+/*
+    This file is part of Mitsuba, a physically based rendering system.
+
+    Copyright (c) 2007-2011 by Wenzel Jakob and others.
+
+    Mitsuba is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License Version 3
+    as published by the Free Software Foundation.
+
+    Mitsuba is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <mitsuba/render/texture.h>
+#include <mitsuba/render/trimesh.h>
+#include <mitsuba/core/properties.h>
+#include <mitsuba/hw/basicshader.h>
+
+MTS_NAMESPACE_BEGIN
+
+/*!\plugin{wireframe}{Wireframe texture}
+ */
+class WireFrame : public Texture {
+public:
+	WireFrame(const Properties &props) : Texture(props) {
+		m_edgeColor = props.getSpectrum("edgeColor", Spectrum(0.0f));
+		m_interiorColor = props.getSpectrum("interiorColor", Spectrum(.5f));
+		m_lineWidth = props.getFloat("lineWidth", .01f);
+	}
+
+	WireFrame(Stream *stream, InstanceManager *manager) 
+	 : Texture(stream, manager) {
+
+		m_edgeColor = Spectrum(stream);
+		m_interiorColor = Spectrum(stream);
+		m_lineWidth = stream->readFloat();
+	}
+
+	void serialize(Stream *stream, InstanceManager *manager) const {
+		Texture::serialize(stream, manager);
+
+		m_edgeColor.serialize(stream);
+		m_interiorColor.serialize(stream);
+		stream->writeFloat(m_lineWidth);
+	}
+
+	Spectrum getValue(const Intersection &its) const {
+		if (!its.shape->getClass()->derivesFrom(MTS_CLASS(TriMesh)))
+			return m_interiorColor;
+
+		const TriMesh *trimesh = static_cast<const TriMesh *>(its.shape);
+		if (its.primIndex >= trimesh->getTriangleCount())
+			return m_interiorColor;
+
+		const Triangle &tri = trimesh->getTriangles()[its.primIndex];
+		const Point *positions = trimesh->getVertexPositions();
+
+		Point pos[] = { positions[tri.idx[0]],
+			positions[tri.idx[1]],
+			positions[tri.idx[2]] };
+
+		Float minDist = std::numeric_limits<Float>::infinity();
+		for (int i=0; i<3; ++i) {
+			Point cur = pos[i], next = pos[(i+1)%3];
+
+			Vector d1 = normalize(next - cur),
+				   d2 = its.p - cur;
+
+			minDist = std::min(minDist, (cur + d1 * dot(d1, d2) - its.p).length());
+		}
+
+		Float value = 1-smoothStep(0, m_lineWidth, minDist);
+
+		return m_edgeColor * value + m_interiorColor * (1-value);
+	}
+
+	bool usesRayDifferentials() const {
+		return false;
+	}
+
+	Spectrum getAverage() const {
+		Spectrum value;
+		/* Approximate ... */
+		for (size_t i=0; i<SPECTRUM_SAMPLES; ++i)
+			value[i] = 0.5f * (m_edgeColor[i] + m_interiorColor[i]);
+		return value;
+	}
+
+	Spectrum getMinimum() const {
+		Spectrum value;
+		for (size_t i=0; i<SPECTRUM_SAMPLES; ++i)
+			value[i] = std::min(m_edgeColor[i], m_interiorColor[i]);
+		return value;
+	}
+
+	Spectrum getMaximum() const {
+		Spectrum value;
+		for (size_t i=0; i<SPECTRUM_SAMPLES; ++i)
+			value[i] = std::max(m_edgeColor[i], m_interiorColor[i]);
+		return value;
+	}
+
+	bool isConstant() const {
+		return false;
+	}
+
+	std::string toString() const {
+		std::ostringstream oss;
+		oss << "WireFrame[" << endl
+			<< "  edgeColor = " << m_edgeColor.toString() << ","
+			<< "  interiorColor = " << m_interiorColor.toString() << ","
+			<< "  lineWidth = " << m_lineWidth << endl
+			<< "]";
+		return oss.str();
+	}
+
+	Shader *createShader(Renderer *renderer) const;
+
+	MTS_DECLARE_CLASS()
+protected:
+	Spectrum m_edgeColor;
+	Spectrum m_interiorColor;
+	Float m_lineWidth;
+};
+
+// ================ Hardware shader implementation ================ 
+
+class WireFrameShader : public Shader {
+public:
+	WireFrameShader(Renderer *renderer, const Spectrum &value) 
+		: Shader(renderer, ETextureShader), m_value(value) {
+	}
+
+	void generateCode(std::ostringstream &oss,
+			const std::string &evalName,
+			const std::vector<std::string> &depNames) const {
+		oss << "uniform vec3 " << evalName << "_value;" << endl
+			<< endl
+			<< "vec3 " << evalName << "(vec2 uv) {" << endl
+			<< "    return " << evalName << "_value;" << endl
+			<< "}" << endl;
+	}
+
+	void resolve(const GPUProgram *program, const std::string &evalName, std::vector<int> &parameterIDs) const {
+		parameterIDs.push_back(program->getParameterID(evalName + "_value", false));
+	}
+
+	void bind(GPUProgram *program, const std::vector<int> &parameterIDs, int &textureUnitOffset) const {
+		program->setParameter(parameterIDs[0], m_value);
+	}
+
+	MTS_DECLARE_CLASS()
+private:
+	Spectrum m_value;
+};
+
+Shader *WireFrame::createShader(Renderer *renderer) const {
+	return new WireFrameShader(renderer, m_interiorColor);
+}
+
+MTS_IMPLEMENT_CLASS(WireFrameShader, false, Shader)
+MTS_IMPLEMENT_CLASS_S(WireFrame, false, Texture)
+MTS_EXPORT_PLUGIN(WireFrame, "Vertex color texture");
+MTS_NAMESPACE_END