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/*

 *  WireframeRenderer.cpp

 *  GEL

 *

 *  Created by J. Andreas Bærentzen on 20/09/08.

 *  Copyright 2008 __MyCompanyName__. All rights reserved.

 *

 */

#include "ManifoldRenderer.h"

#include <algorithm>

#include <string>

#include <cstdlib>

#include <CGLA/Mat3x3d.h>

#include <GLGraphics/glsl_shader.h>

#include <HMesh/Manifold.h>

#include <HMesh/AttributeVector.h>

#include <HMesh/curvature.h>

using namespace CGLA;

using namespace HMesh;

using namespace std;

namespace GLGraphics

{

    GLuint get_noise_texture_id()

    {

        static GLuint texname=0;

        static bool was_here = false;

        if(!was_here)

        {

            was_here = true;

            int width = 32;

            int height = 32;

            int depth = 32;

            vector<unsigned char> texels(width*height*depth);

            for (int i = 0; i < width*height*depth; ++i)

            {

                int intensity = 255.0 * (float(gel_rand()) / GEL_RAND_MAX);

                texels[i] = (unsigned char) intensity;

            }

            glGenTextures(1, &texname);	

            glBindTexture(GL_TEXTURE_3D, texname);	

            glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

            glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

            glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_S, GL_REPEAT);

            glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_T, GL_REPEAT);

            glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_R, GL_REPEAT);

            glTexImage3D(GL_TEXTURE_3D, 0, GL_INTENSITY8, width, height, depth, 0, GL_RED, GL_UNSIGNED_BYTE, &texels[0]);

        }

        return texname;

    }

    int WireframeRenderer::maximum_face_valency(const Manifold& m)

    {

        int max_val = 0;

        for(FaceIDIterator f = m.faces_begin(); f != m.faces_end(); ++f)

            max_val = max(max_val, no_edges(m, *f));

        return max_val;

    }

    WireframeRenderer::WireframeRenderer(HMesh::Manifold& m, bool smooth): idbuff_renderer(0)

    {

        if(GLEW_EXT_geometry_shader4 && maximum_face_valency(m) > 3)

        {

            GLint viewp[4];

            glGetIntegerv(GL_VIEWPORT,viewp);

            idbuff_renderer = new IDBufferWireframeRenderer(viewp[2], viewp[3], m);

        }

        else

        {

            glNewList(display_list,GL_COMPILE);

            if(GLEW_EXT_geometry_shader4)

                draw_triangles_in_wireframe(m,smooth, Vec3f(1,0,0));				

            else

                draw_wireframe_oldfashioned(m,smooth, Vec3f(1,0,0));

            glEndList();

        }

    }

    void WireframeRenderer::draw()

    {

        if(idbuff_renderer)

            idbuff_renderer->draw(Vec3f(1,0,0),Vec3f(1)); 

        else

            glCallList(display_list);

    }

    void SimpleShaderRenderer::init_shaders(const std::string& vss, 

                                            const std::string& fss)

    {

        vs = create_glsl_shader(GL_VERTEX_SHADER, vss);

        print_glsl_program_log(vs);

        fs = create_glsl_shader(GL_FRAGMENT_SHADER, fss);

        print_glsl_program_log(fs);

        prog = glCreateProgram();

        if(vs) glAttachShader(prog, vs);

        if(fs) glAttachShader(prog, fs);

        glLinkProgram(prog);

        print_glsl_program_log(prog);

    }

    void SimpleShaderRenderer::compile_display_list(const Manifold& m, bool smooth)

    {

        glNewList(display_list,GL_COMPILE);

        GLGraphics::draw(m, smooth);

        glEndList();	

    }

    void SimpleShaderRenderer::draw()

    {

        GLint old_prog;

        glGetIntegerv(GL_CURRENT_PROGRAM, &old_prog);

        glUseProgram(prog);

        glCallList(display_list);

        glUseProgram(old_prog);

    }

    const string NormalRenderer::vss = 

    "varying vec3 _n;\n"

    "varying vec3 v;\n"

    "\n"

    "void main(void)\n"

    "{\n"

    "	gl_Position = ftransform();\n"

    "	v = vec3(gl_ModelViewMatrix * gl_Vertex);\n"

    "	_n = normalize(gl_NormalMatrix * gl_Normal);\n"

    "}\n";

    const string NormalRenderer::fss = 

    "varying vec3 _n;\n"

    "varying vec3 v;\n"

    "\n"

    "void main(void)\n"

    "{\n"

    "   vec3 n = normalize(_n);\n"

    "	vec3 l = normalize(-v);\n"

    "	vec3 e = l;\n"

    "	vec3 r = normalize(2.0*dot(l, n)*n - l);\n"

    "	\n"

    "	vec4 a = vec4(0.0,0.1,.3,1.0);\n"

    "   float dot_ln = abs(dot(l, n));\n"

    "	vec4 d = vec4(0.7) * dot_ln;\n"

    "	vec4 s = vec4(0.3)*smoothstep(0.98,0.9999,dot(r, e));\n"

    "	\n"

    "	gl_FragColor =  d+s;\n"

    "}\n";

    const string ReflectionLineRenderer::vss = 

    "varying vec3 _n;\n"

    "varying vec3 v;\n"

    "\n"

    "void main(void)\n"

    "{\n"

    "	gl_Position = ftransform();\n"

    "	v = vec3(gl_ModelViewMatrix * gl_Vertex);\n"

    "	_n = normalize(gl_NormalMatrix * gl_Normal);\n"

    "}\n";

    const string ReflectionLineRenderer::fss = 

    "uniform float detail;\n"

    "\n"

    "varying vec3 _n;\n"

    "varying vec3 v;\n"

    "\n"

    "void main(void)\n"

    "{\n"

    "   vec3 n = normalize(_n);\n"

    "	// calculate the reflection\n"

    "	vec3 r = normalize(2.0*dot(-v, n)*n + v);\n"

    "	vec3 viewer_lightdir = vec3(0, 0, 1.0);\n"

    "   float diff  = dot(n,viewer_lightdir);\n"

    "	\n"

    "	vec2 r2 = normalize(vec2(r[0], r[2]));\n"

    "	vec2 x = vec2(1, 0);\n"

    "	float angle = acos(dot(r2, x));\n"

    "	\n"

    "	// decide if we hit a white or black ring, based on y value\n"

    "	gl_FragColor = diff * vec4(1.0) + smoothstep(0.8, 1.0,cos(13.0*angle)) * vec4(-1.0);\n"

    "}\n";

    const string IsophoteLineRenderer::vss = 

    "varying vec3 _n;\n"

    "varying vec3 v;\n"

    "\n"

    "void main(void)\n"

    "{\n"

    "	gl_Position = ftransform();\n"

    "	v = vec3(gl_ModelViewMatrix * gl_Vertex);\n"

    "	_n = normalize(gl_NormalMatrix * gl_Normal);\n"

    "}\n";

    const string IsophoteLineRenderer::fss = 

    "uniform float detail;\n"

    "\n"

    "varying vec3 _n;\n"

    "varying vec3 v;\n"

    "\n"

    "void main(void)\n"

    "{\n"

    "   vec3 n = normalize(_n);\n"

    "	vec3 viewer_lightdir = vec3(0, 0, 1.0);\n"

    "	vec3 isophote_lightdir = viewer_lightdir;\n"

    "	float angle = acos(dot(n, isophote_lightdir));\n"

    "   float diff  = dot(n,viewer_lightdir);\n"

    "	\n"

    "	// decide if we hit a white or black ring, based on y value\n"

    "	gl_FragColor = diff * vec4(1.0) + smoothstep(0.8, 1.0,cos(20.0*angle)) * vec4(-1.0);\n"

    "}\n";

    const string ToonRenderer::vss = 

    "varying vec3 _n;\n"

    "varying vec3 v;\n"

    "\n"

    "void main(void)\n"

    "{\n"

    "	gl_Position = ftransform();\n"

    "	v = vec3(gl_ModelViewMatrix * gl_Vertex);\n"

    "	_n = normalize(gl_NormalMatrix * gl_Normal);\n"

    "}\n";

    const string ToonRenderer::fss = 

    "varying vec3 _n;\n"

    "varying vec3 v;\n"

    "\n"

    "void main(void)\n"

    "{\n"

    "   vec3 n = normalize(_n);\n"

    "	vec3 l = normalize(-v);\n"

    "	vec3 e = l;\n"

    "	vec3 r = normalize(2.0*dot(l, n)*n - l);\n"

    "	\n"

    "	vec4 a = vec4(0.0,0.1,.3,1.0);\n"

    "   float dot_ln = abs(dot(l, n));\n"

    "	vec4 d = vec4(0.7,0.7,0.0,1.0) * 0.25 * (smoothstep(0.23,0.25,dot_ln)+smoothstep(0.45,0.47,dot_ln)+smoothstep(0.7,0.72,dot_ln)+smoothstep(0.9,0.92,dot_ln));\n"

    "	vec4 s = vec4(0.5,0.3,0.4,1.0)*smoothstep(0.96,0.98,dot(r, e));\n"

    "	\n"

    "	gl_FragColor =  d+s;\n"

    "}\n";

    void GlazedRenderer::draw()

    {

        GLint old_prog;

        glGetIntegerv(GL_CURRENT_PROGRAM, &old_prog);

        glUseProgram(prog);

        glBindTexture(GL_TEXTURE_3D, get_noise_texture_id());

        glUniform1iARB(glGetUniformLocationARB(prog, "noise_tex"),0);

        glUniform1fARB(glGetUniformLocationARB(prog, "noise_scale"),12.0/bsphere_rad);

        glCallList(display_list);

        glUseProgram(old_prog);

    }

    const string GlazedRenderer::vss = 

    "varying vec3 _n;\n"

    "varying vec3 v;\n"

    "varying vec3 v_obj;\n"

    "\n"

    "void main(void)\n"

    "{\n"

    "	gl_Position = ftransform();\n"

    "   v_obj = gl_Vertex.xyz;\n"

    "	v = vec3(gl_ModelViewMatrix * gl_Vertex);\n"

    "	_n = normalize(gl_NormalMatrix * gl_Normal);\n"

    "}\n"

    "\n";

    const string GlazedRenderer::fss =

    "uniform sampler3D noise_tex;\n"

    "uniform float noise_scale;\n"

    "varying vec3 _n;\n"

    "varying vec3 v;\n"

    "varying vec3 v_obj;\n"

    "\n"

    "vec4 glazed_shader(vec4 mat_col,  vec4 light_col, vec3 light_dir)\n"

    "{\n"

    "   vec3 n = normalize(_n);\n"

    "	vec3 e = normalize(-v);\n"

    "	vec3 r = normalize(2.0*dot(e, n)*n - e);\n"

    "	float d = max(0.05,dot(light_dir, n));\n"

    "	vec4 diff = mat_col * light_col *d; 	\n"

    "	vec4 refl = smoothstep(0.7,0.75,dot(r,light_dir)) * light_col;\n"

    "	return 0.15*refl + diff;\n"

    "}\n"

    "\n"

    "void main(void)\n"

    "{\n"

    "	vec4 mat_col = vec4(0.9,1.0,0.4,1.0) + vec4(-0.1,-0.1,0.12,0.0) * texture3D(noise_tex, noise_scale*v_obj).x\n"

    " + vec4(0.05) * texture3D(noise_tex, 500.0*v_obj).x;\n"

    "	\n"

    "	vec3 light0_dir = vec3(0.0,1.0,0.0);\n"

    "	vec4 light0_col = vec4(0.7,0.9,1.0,1.0);\n"

    "	\n"

    "	vec3 light1_dir = vec3(0.0,0.0,1.0);\n"

    "	vec4 light1_col = vec4(1.0,1.0,0.7,1.0);\n"

    "	\n"

    "	gl_FragColor = \n"

    "	0.5*glazed_shader(mat_col, light0_col, light0_dir)+\n"

    "	0.5*glazed_shader(mat_col, light1_col, light1_dir);\n"

    "	\n"

    "	gl_FragColor.a = 1.0;\n"

    "}\n";

    const string ScalarFieldRenderer::vss =

    "	attribute float scalar;\n"

    "	varying vec3 _normal;\n"

    "	varying float s;\n"

    "	\n"

    "	void main(void)\n"

    "	{\n"

    "		gl_Position =  ftransform();\n"

    "		_normal = normalize(gl_NormalMatrix * gl_Normal);\n"

    "		s=scalar;\n"

    "	}\n";

    const string ScalarFieldRenderer::fss = 	

    "	varying vec3 _normal;\n"

    "	varying float s;\n"

    "	uniform float scalar_max;\n"

    "   uniform float gamma;\n"

    "	const vec3 light_dir = vec3(0,0,1);\n"

    "	\n"

    "	void main()\n"

    "	{\n"

    "       vec3 normal = normalize(_normal);\n"

    "		float dot_ln = max(0.0,dot(light_dir, normal));\n"

    "		\n"

    "		float s_norm = s/scalar_max;\n"

    "		float stripe_signal = 100.0 * s_norm;\n"

    "		vec4 stripe_col = abs(stripe_signal) < 3.14 ? vec4(0,0,0,0) : vec4(.1,.1,.1,0);\n"

    "		\n"

    "		gl_FragColor = s_norm * vec4(-1,0,1,0);\n"

    "       gl_FragColor *= dot_ln;\n"

    "       gl_FragColor.r = pow(gl_FragColor.r, 1.0/gamma);\n"

    "       gl_FragColor.g = pow(gl_FragColor.g, 1.0/gamma);\n"

    "       gl_FragColor.b = pow(gl_FragColor.b, 1.0/gamma);\n"

    "		gl_FragColor += stripe_col * smoothstep(0.8,1.0,cos(stripe_signal));\n"

    "	}\n";

    ScalarFieldRenderer::ScalarFieldRenderer(const Manifold& m, 

                                             bool smooth, 

                                             VertexAttributeVector<double>& field, 

                                             double max_val, float gamma): SimpleShaderRenderer(vss, fss)

    {

        GLint old_prog;

        glGetIntegerv(GL_CURRENT_PROGRAM, &old_prog);

        glUseProgram(prog);

        GLuint scalar_attrib = glGetAttribLocation(prog, "scalar");

        glUniform1fARB(glGetUniformLocationARB(prog, "scalar_max"), max_val);

        //    static float& gamma = CreateCVar("display.scalar_field_renderer.gamma",2.2f);

        glUniform1fARB(glGetUniformLocationARB(prog, "gamma"), gamma);

        glNewList(display_list,GL_COMPILE);

        for(FaceIDIterator f = m.faces_begin(); f != m.faces_end(); ++f){      

            if(!smooth) 

                glNormal3fv(normal(m, *f).get());

            if(no_edges(m, *f)== 3) 

                glBegin(GL_TRIANGLES);

            else 

                glBegin(GL_POLYGON);

            for(HalfEdgeWalker w = m.halfedgewalker(*f); !w.full_circle(); w = w.circulate_face_ccw()){

                Vec3d n(normal(m, w.vertex()));

                if(smooth) 

                    glNormal3dv(n.get());

                glVertexAttrib1d(scalar_attrib, field[w.vertex()]);

                glVertex3fv(m.pos(w.vertex()).get());

            }

            glEnd();

        }

        glEndList();	

        glUseProgram(old_prog);

    }

    const string AmbientOcclusionRenderer::vss =

    "	attribute float scalar;\n"

    "	varying vec3 _normal;\n"

    "	varying float s;\n"

    "	\n"

    "	void main(void)\n"

    "	{\n"

    "		gl_Position =  ftransform();\n"

    "		_normal = normalize(gl_NormalMatrix * gl_Normal);\n"

    "		s=scalar;\n"

    "	}\n";

    const string AmbientOcclusionRenderer::fss = 	

    "	varying vec3 _normal;\n"

    "	varying float s;\n"

    "	uniform float scalar_max;\n"

    "	const vec3 light_dir = vec3(0,0,1);\n"

    "	\n"

    "	void main()\n"

    "	{\n"

    "   vec3 normal = normalize(_normal);\n"

    "		float dot_ln = max(0.0,dot(light_dir, normal));\n"

    "		\n"

    "		float s_norm = min(1.0,s/scalar_max+1.0);\n"

    "		\n"

    "		gl_FragColor = s_norm * vec4(1.0);\n"

    "       gl_FragColor *= dot_ln;\n"

    "       gl_FragColor.r = pow(gl_FragColor.r, 1.0);\n"

    "       gl_FragColor.g = pow(gl_FragColor.g, 1.0);\n"

    "       gl_FragColor.b = pow(gl_FragColor.b, 1.0);\n"

    "	}\n";

    AmbientOcclusionRenderer::AmbientOcclusionRenderer(const Manifold& m, bool smooth, VertexAttributeVector<double>& field, double max_val):

    SimpleShaderRenderer(vss,fss)

    {	

        GLint old_prog;

        glGetIntegerv(GL_CURRENT_PROGRAM, &old_prog);

        glUseProgram(prog);

        GLuint scalar_attrib = glGetAttribLocation(prog, "scalar");

        glUniform1fARB(glGetUniformLocationARB(prog, "scalar_max"), max_val);

        glNewList(display_list,GL_COMPILE);

        for(FaceIDIterator f = m.faces_begin(); f != m.faces_end(); ++f){

            if(!smooth) 

                glNormal3fv(normal(m, *f).get());

            if(no_edges(m, *f)== 3) 

                glBegin(GL_TRIANGLES);

            else 

                glBegin(GL_POLYGON);

            for(HalfEdgeWalker w = m.halfedgewalker(*f); !w.full_circle(); w = w.circulate_face_ccw())

            {

                Vec3d n(normal(m, w.vertex()));

                if(smooth) 

                    glNormal3dv(n.get());

                glVertexAttrib1d(scalar_attrib, field[w.vertex()]);

                glVertex3fv(m.pos(w.vertex()).get());

            }

            glEnd();

        }

        glEndList();	

        glUseProgram(old_prog);

    }

    LineFieldRenderer::LineFieldRenderer(const Manifold& m, bool smooth, VertexAttributeVector<Vec3d>& lines, float _r, float line_scale, float noise_scale, float noise_amplitude): 

    SimpleShaderRenderer(vss,fss), r(_r)

    {

        GLint old_prog;

        glGetIntegerv(GL_CURRENT_PROGRAM, &old_prog);

        glUseProgram(prog);	

        //    static float& line_scale = CreateCVar("display.line_field_renderer.line_length", .015f);

        //    static float& noise_scale = CreateCVar("display.line_field_renderer.noise_scale", 12.0f/r);

        //    static float& noise_amplitude = CreateCVar("display.line_field_renderer.noise_amplitude", .06f);

        glUniform1fARB(glGetUniformLocationARB(prog, "scale_line"),line_scale);

        glUniform1fARB(glGetUniformLocationARB(prog, "noise_scale"),noise_scale);

        glUniform1fARB(glGetUniformLocationARB(prog, "noise_amplitude"),noise_amplitude);	

        glUniform1iARB(glGetUniformLocationARB(prog, "noise_tex"),0);

        GLuint direction = glGetAttribLocation(prog, "direction");	

        glNewList(display_list,GL_COMPILE);

        for(FaceIDIterator f = m.faces_begin(); f != m.faces_end(); ++f){

            if(!smooth) 

                glNormal3fv(normal(m, *f).get());

            if(no_edges(m, *f) == 3) 

                glBegin(GL_TRIANGLES);

            else 

                glBegin(GL_POLYGON);

            for(HalfEdgeWalker w = m.halfedgewalker(*f); !w.full_circle(); w = w.circulate_face_ccw()){

                Vec3d n(normal(m, w.vertex()));

                if(smooth) 

                    glNormal3dv(n.get());

                Vec3d d = lines[w.vertex()];

                d = normalize(d-n*dot(n,d));

                glVertexAttrib3dv(direction, d.get());

                glVertex3fv(m.pos(w.vertex()).get());

            }

            glEnd();

        }

        glBindTexture(GL_TEXTURE_3D, 0);

        glEndList();	

        glUseProgram(old_prog);

    }

    void LineFieldRenderer::draw()

    {

        GLint old_prog;

        glGetIntegerv(GL_CURRENT_PROGRAM, &old_prog);

        glUseProgram(prog);

        glBindTexture(GL_TEXTURE_3D, get_noise_texture_id());

        glCallList(display_list);

        glBindTexture(GL_TEXTURE_3D, 0);

        glUseProgram(old_prog);	

    }

    const string LineFieldRenderer::vss = 

    "attribute vec3 direction;\n"

    "varying vec3 _n;\n"

    "varying vec3 dir_obj;\n"

    "varying vec3 v_obj;\n"

    "\n"

    "void main(void)\n"

    "{\n"

    "	gl_Position = ftransform();\n"

    "   v_obj = gl_Vertex.xyz;\n"

    "	dir_obj = direction;\n"

    "	_n = normalize(gl_NormalMatrix * gl_Normal);\n"

    "}\n";

    const string LineFieldRenderer::fss =

    "uniform sampler3D noise_tex;\n"

    "uniform float scale_line;\n"

    "uniform float noise_amplitude;\n"

    "uniform float noise_scale;\n"

    "varying vec3 _n;\n"

    "varying vec3 dir_obj;\n"

    "varying vec3 v_obj;\n"

    "\n"

    "float tex(vec3 p) {return smoothstep(0.23,0.25,texture3D(noise_tex, p).x);}\n"

    "void main(void)\n"

    "{\n"

    "   vec3 n = normalize(_n);\n"

    "   float I = "

    "             tex(noise_scale*v_obj + 6.0*scale_line*dir_obj) + \n"

    "             tex(noise_scale*v_obj - 6.0*scale_line*dir_obj) + \n"

    "             tex(noise_scale*v_obj + 5.0*scale_line*dir_obj) + \n"

    "             tex(noise_scale*v_obj - 5.0*scale_line*dir_obj) + \n"

    "             tex(noise_scale*v_obj + 4.0*scale_line*dir_obj) + \n"

    "             tex(noise_scale*v_obj - 4.0*scale_line*dir_obj) + \n"

    "             tex(noise_scale*v_obj + 3.0*scale_line*dir_obj) + \n"

    "             tex(noise_scale*v_obj - 3.0*scale_line*dir_obj) + \n"

    "             tex(noise_scale*v_obj + 2.0*scale_line*dir_obj) + \n"

    "             tex(noise_scale*v_obj - 2.0*scale_line*dir_obj) + \n"

    "             tex(noise_scale*v_obj + 1.0*scale_line*dir_obj) + \n"

    "             tex(noise_scale*v_obj - 1.0*scale_line*dir_obj) + \n"

    "			  tex(noise_scale*v_obj); \n"

    "	\n"

    "   float diff = max(0.0,dot(n,vec3(0.0, 0.0, 1.0)));\n"

    "	gl_FragColor.rgb = vec3(1)*diff*I*(1.0/13.0);\n"

    "	gl_FragColor.a = 1.0;\n"

    "}\n";

    const string DualVertexRenderer::vss = 

    "#version 120\n"

    "#extension GL_EXT_gpu_shader4 : enable\n"

    "varying vec4 diffuseIn;\n"

    "varying vec3 _normalIn;\n"

    "void main(void)\n"

    "{\n"

    "   diffuseIn = gl_Color;\n"

    "   _normalIn = normalize(gl_NormalMatrix*gl_Normal);\n"

    "   gl_Position =  ftransform();\n"

    "}\n";

    const string DualVertexRenderer::gss = 

    "#version 120\n"

    "#extension GL_EXT_gpu_shader4 : enable\n"

    "#extension GL_EXT_geometry_shader4 : enable\n"

    "\n"

    "varying in vec4 diffuseIn[3];\n"

    "varying in vec3 _normalIn[3];\n"

    "varying vec4 diffuse[3];\n"

    "varying float f;\n"

    "varying vec3 _normal;\n"

    "void main(void)\n"

    "{\n"

    "  diffuse[0] = diffuseIn[0];\n"

    "  diffuse[1] = diffuseIn[1];\n"

    "  diffuse[2] = diffuseIn[2];\n"

    "\n"

    "  f = diffuseIn[0].a;\n"

    "  gl_Position = gl_PositionIn[0];\n"

    "  _normal = _normalIn[0];\n"

    "  EmitVertex();\n"

    "	\n"

    "  f = diffuseIn[1].a;\n"

    "  gl_Position = gl_PositionIn[1];\n"

    "  _normal = _normalIn[1];\n"

    "  EmitVertex();\n"

    "\n"

    "  f = diffuseIn[2].a;\n"

    "  gl_Position = gl_PositionIn[2];\n"

    "  _normal = _normalIn[2];\n"

    "  EmitVertex();\n"

    "\n"

    "  EndPrimitive();\n"

    "}\n";

    const string DualVertexRenderer::fss =

    "#version 120\n"

    "#extension GL_EXT_gpu_shader4 : enable\n"

    "\n"

    "varying float f;\n"

    "varying vec4 diffuse[3];\n"

    "varying vec3 _normal;\n"

    "\n"

    "void main(void)\n"

    "{\n"

    "   vec3 normal = normalize(_normal);\n"

    "   float col_idx=0;\n"

    "   if(f>diffuse[0].g && f<diffuse[0].b)\n"

    "      col_idx = diffuse[0].r;\n"

    "   else if(f>diffuse[1].g && f<diffuse[1].b)\n"

    "      col_idx = diffuse[1].r;\n"

    "   else if(f>diffuse[2].g && f<diffuse[2].b)\n"

    "      col_idx = diffuse[2].r;\n"

    "   vec4 col = col_idx < .5 ? vec4(1,0,0,0) : vec4(0,0,1,0);\n"

    "\n"

    " 	gl_FragColor =col*dot(normal, vec3(0,0,1));\n"

    "}\n";

    DualVertexRenderer::DualVertexRenderer(const HMesh::Manifold& m, VertexAttributeVector<Vec4d>& field)

    {		

        // Create the program

        static GLuint prog = glCreateProgram();

        static bool was_here = false;

        if(!was_here)

        {

            was_here = true;

            // Create s	haders directly from file

            static GLuint vs = create_glsl_shader(GL_VERTEX_SHADER, vss);

            static GLuint gs = create_glsl_shader(GL_GEOMETRY_SHADER_EXT, gss);

            static GLuint fs = create_glsl_shader(GL_FRAGMENT_SHADER, fss);

            // Attach all shaders

            if(vs) glAttachShader(prog, vs);

            if(gs) glAttachShader(prog, gs);

            if(fs) glAttachShader(prog, fs);

            // Specify input and output for the geometry shader. Note that this must be

            // done before linking the program.

            glProgramParameteriEXT(prog,GL_GEOMETRY_INPUT_TYPE_EXT,GL_TRIANGLES);

            glProgramParameteriEXT(prog,GL_GEOMETRY_VERTICES_OUT_EXT,3);

            glProgramParameteriEXT(prog,GL_GEOMETRY_OUTPUT_TYPE_EXT,GL_TRIANGLE_STRIP);

            // Link the program object and print out the info log

            glLinkProgram(prog);

        }

        GLint old_prog;

        glGetIntegerv(GL_CURRENT_PROGRAM, &old_prog);

        glNewList(display_list,GL_COMPILE);

        glUseProgram(prog);

        for(FaceIDIterator f = m.faces_begin(); f != m.faces_end(); ++f){

            if(no_edges(m, *f) != 3) 

                continue;

            else 

                glBegin(GL_TRIANGLES);

            for(HalfEdgeWalker w = m.halfedgewalker(*f); !w.full_circle(); w = w.circulate_face_ccw()){

                Vec3d n(normal(m, w.vertex()));

                glNormal3dv(n.get());

                glColor4dv(field[w.vertex()].get());

                glVertex3fv(m.pos(w.vertex()).get());

            }

            glEnd();

        }

        glUseProgram(old_prog);

        glEndList();	

    }

}