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/**************************************************************************/
/* Copyright 2012 Tim Day */
/* */
/* This file is part of Evolvotron */
/* */
/* Evolvotron is free software: you can redistribute it and/or modify */
/* it under the terms of the GNU General Public License as published by */
/* the Free Software Foundation, either version 3 of the License, or */
/* (at your option) any later version. */
/* */
/* Evolvotron 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 Evolvotron. If not, see <http://www.gnu.org/licenses/>. */
/**************************************************************************/
/*! \file
\brief Interfaces and implementation for specific Function classes.
As much as possible of the implementation should be pushed into the FunctionBoilerplate template.
*/
#ifndef _functions_render_h_
#define _functions_render_h_
#include "common.h"
#include "function_boilerplate.h"
//------------------------------------------------------------------------------------------
//! Rays intersecting a textured unit sphere
/*! arg(0) is background
arg(1) is 3D texture for sphere
param(0,1,2) is light source direction
p.x, p.y is the 2D position of a ray from infinity travelling in direction (0 0 1)
*/
FUNCTION_BEGIN(FunctionOrthoSphereShaded,3,2,false,FnRender)
//! Evaluate function.
virtual const XYZ evaluate(const XYZ& p) const
{
const real pr2=p.x()*p.x()+p.y()*p.y();
if (pr2<1.0)
{
const real z=-sqrt(1.0-pr2);
const XYZ n(p.x(),p.y(),z);
const XYZ lu(param(0),param(1),param(2));
const XYZ l(lu.normalised());
const real i=0.5*(1.0+l%n); // In range 0-1
return i*arg(1)(n);
}
else
{
return arg(0)(p);
}
}
FUNCTION_END(FunctionOrthoSphereShaded)
//------------------------------------------------------------------------------------------
//! Rays intersecting a textured unit sphere, with bump mapping
/*! arg(0) is background
arg(1) is 3D texture for sphere
arg(2) is bump-map for sphere (take magnitude2)
param(0,1,2) is light source direction
p.x, p.y is the 2D position of a ray from infinity travelling in direction (0 0 1)
*/
FUNCTION_BEGIN(FunctionOrthoSphereShadedBumpMapped,3,3,false,FnRender)
//! Evaluate function.
virtual const XYZ evaluate(const XYZ& p) const
{
const real pr2=p.x()*p.x()+p.y()*p.y();
if (pr2<1.0)
{
const real z=-sqrt(1.0-pr2);
const XYZ n(p.x(),p.y(),z);
// Tangent vectors
const XYZ east((XYZ(0.0,1.0,0.0)*n).normalised());
const XYZ north(n*east);
const real e0=(arg(2)(n-epsilon()*east)).magnitude2();
const real e1=(arg(2)(n+epsilon()*east)).magnitude2();
const real n0=(arg(2)(n-epsilon()*north)).magnitude2();
const real n1=(arg(2)(n+epsilon()*north)).magnitude2();
const real de=(e1-e0)*inv_epsilon2();
const real dn=(n1-n0)*inv_epsilon2();
const XYZ perturbed_n((n-east*de-north*dn).normalised());
const XYZ lu(param(0),param(1),param(2));
const XYZ l(lu.normalised());
const real i=0.5*(1.0+l%perturbed_n); // In range 0-1
return i*arg(1)(n);
}
else
{
return arg(0)(p);
}
}
FUNCTION_END(FunctionOrthoSphereShadedBumpMapped)
//------------------------------------------------------------------------------------------
//! Rays reflecting off a unit sphere
/*! arg(0) is background
arg(1) sampled using a normalised vector defines an environment for reflected rays
p.x, p.y is the 2D position of a ray from infinity travelling in direction (0 0 1)
*/
FUNCTION_BEGIN(FunctionOrthoSphereReflect,0,2,false,FnRender)
//! Evaluate function.
virtual const XYZ evaluate(const XYZ& p) const
{
const real pr2=p.x()*p.x()+p.y()*p.y();
if (pr2<1.0)
{
const real z=-sqrt(1.0-pr2);
// This is on surface of unit radius sphere - no need to normalise
XYZ n(p.x(),p.y(),z);
// The ray _towards_ the viewer v is (0 0 -1)
const XYZ v(0.0,0.0,-1.0);
// The reflected ray is (2n.v)n-v
const XYZ reflected((2.0*(n%v))*n-v);
return arg(1)(reflected);
}
else
{
return arg(0)(p);
}
}
FUNCTION_END(FunctionOrthoSphereReflect)
//------------------------------------------------------------------------------------------
//! Rays reflecting off a bump mapped unit sphere
/*! arg(0) is background
arg(1) sampled using a normalised vector defines an environment for reflected rays
arg(2) is bump map
p.x, p.y is the 2D position of a ray from infinity travelling in direction (0 0 1)
*/
FUNCTION_BEGIN(FunctionOrthoSphereReflectBumpMapped,0,3,false,FnRender)
//! Evaluate function.
virtual const XYZ evaluate(const XYZ& p) const
{
const real pr2=p.x()*p.x()+p.y()*p.y();
if (pr2<1.0)
{
const real z=-sqrt(1.0-pr2);
// This is on surface of unit radius sphere - no need to normalise
XYZ n(p.x(),p.y(),z);
// Tangent vectors
const XYZ east((XYZ(0.0,1.0,0.0)*n).normalised());
const XYZ north(n*east);
const real e0=(arg(2)(n-epsilon()*east)).magnitude2();
const real e1=(arg(2)(n+epsilon()*east)).magnitude2();
const real n0=(arg(2)(n-epsilon()*north)).magnitude2();
const real n1=(arg(2)(n+epsilon()*north)).magnitude2();
const real de=(e1-e0)*inv_epsilon2();
const real dn=(n1-n0)*inv_epsilon2();
const XYZ perturbed_n((n-east*de-north*dn).normalised());
// The ray _towards_ the viewer is (0 0 -1)
const XYZ v(0.0,0.0,-1.0);
// The reflected ray is (2n.v)n-v
const XYZ reflected((2.0*(perturbed_n%v))*perturbed_n-v);
return arg(1)(reflected);
}
else
{
return arg(0)(p);
}
}
FUNCTION_END(FunctionOrthoSphereReflectBumpMapped)
//------------------------------------------------------------------------------------------
#endif
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