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/*
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* wireframe.cpp
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* GEL
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*
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* Created by J. Andreas Bærentzen on 05/08/08.
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* Copyright 2008 __MyCompanyName__. All rights reserved.
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*
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*/
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#include <iostream>
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#include "glsl_shader.h"
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#include "wireframe.h"
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using namespace std;
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namespace
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{
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const string vp =
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"#version 120\n"
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"#extension GL_EXT_gpu_shader4 : enable\n"
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"\n"
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"void main(void)\n"
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"{\n"
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" gl_Position = ftransform();\n"
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"}\n";
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const string gp =
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"#version 120\n"
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"#extension GL_EXT_gpu_shader4 : enable\n"
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"\n"
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"uniform vec2 WIN_SCALE;\n"
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"noperspective varying vec3 dist;\n"
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"void main(void)\n"
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"{\n"
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" vec2 p0 = WIN_SCALE * gl_PositionIn[0].xy/gl_PositionIn[0].w;\n"
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" vec2 p1 = WIN_SCALE * gl_PositionIn[1].xy/gl_PositionIn[1].w;\n"
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" vec2 p2 = WIN_SCALE * gl_PositionIn[2].xy/gl_PositionIn[2].w;\n"
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" \n"
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" vec2 v0 = p2-p1;\n"
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" vec2 v1 = p2-p0;\n"
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" vec2 v2 = p1-p0;\n"
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" float area = abs(v1.x*v2.y - v1.y * v2.x);\n"
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"\n"
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" dist = vec3(area/length(v0),0,0);\n"
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" gl_Position = gl_PositionIn[0];\n"
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" EmitVertex();\n"
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" \n"
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" dist = vec3(0,area/length(v1),0);\n"
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" gl_Position = gl_PositionIn[1];\n"
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" EmitVertex();\n"
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"\n"
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" dist = vec3(0,0,area/length(v2));\n"
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" gl_Position = gl_PositionIn[2];\n"
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" EmitVertex();\n"
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"\n"
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" EndPrimitive();\n"
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"}\n";
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const string fp =
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"#version 120\n"
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"#extension GL_EXT_gpu_shader4 : enable\n"
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"\n"
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"noperspective varying vec3 dist;\n"
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"const vec4 WIRE_COL = vec4(1.0,0.0,0.0,1);\n"
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"const vec4 FILL_COL = vec4(1,1,1,1);\n"
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"\n"
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"void main(void)\n"
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"{\n"
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" float d = min(dist[0],min(dist[1],dist[2]));\n"
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" // Compute intensity\n"
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"\n"
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" float I = exp2(-2*d*d);\n"
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" gl_FragColor = I*WIRE_COL + (1.0 - I)*FILL_COL;\n"
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"}\n";
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static GLhandleARB prog_P0;
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}
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void initialize_wireframe_shaders()
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{
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static bool washere = false;
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if(!washere)
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{
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washere = true;
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// Create s haders directly from file
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GLuint vs = create_glsl_shader(GL_VERTEX_SHADER, vp);
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GLuint gs = create_glsl_shader(GL_GEOMETRY_SHADER_EXT, gp);
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GLuint fs = create_glsl_shader(GL_FRAGMENT_SHADER, fp);
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// Create the program
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prog_P0 = glCreateProgram();
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// Attach all shaders
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if(vs) glAttachShader(prog_P0, vs);
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if(gs) glAttachShader(prog_P0, gs);
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if(fs) glAttachShader(prog_P0, fs);
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// Specify input and output for the geometry shader. Note that this must be
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// done before linking the program.
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glProgramParameteriEXT(prog_P0,GL_GEOMETRY_INPUT_TYPE_EXT,GL_TRIANGLES);
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glProgramParameteriEXT(prog_P0,GL_GEOMETRY_VERTICES_OUT_EXT,3);
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glProgramParameteriEXT(prog_P0,GL_GEOMETRY_OUTPUT_TYPE_EXT,GL_TRIANGLE_STRIP);
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// Link the program object and print out the info log
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glLinkProgram(prog_P0);
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}
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}
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void enable_wireframe()
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{
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glUseProgram(prog_P0);
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GLint vpdim[4];
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glGetIntegerv(GL_VIEWPORT,vpdim);
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// Set the value of a uniform
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glUniform2f(glGetUniformLocation(prog_P0,"WIN_SCALE"), vpdim[2]/2,vpdim[3]/2);
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}
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