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/*
* Adapted from Open Shading Language with this license:
*
* Copyright (c) 2009-2010 Sony Pictures Imageworks Inc., et al.
* All Rights Reserved.
*
* Modifications Copyright 2011, Blender Foundation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of Sony Pictures Imageworks nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef CCL_OSLUTIL_H
#define CCL_OSLUTIL_H
// Return wireframe opacity factor [0, 1] given a geometry type in
// ("triangles", "polygons" or "patches"), and a line_width in raster
// or world space depending on the last (raster) boolean argument.
//
float wireframe(string edge_type, float line_width, int raster)
{
// ray differentials are so big in diffuse context that this function would always return "wire"
if (raytype("path:diffuse")) return 0.0;
int np = 0;
point p[64];
float pixelWidth = 1;
if (edge_type == "triangles")
{
np = 3;
if (!getattribute("geom:trianglevertices", p))
return 0.0;
}
else if (edge_type == "polygons" || edge_type == "patches")
{
getattribute("geom:numpolyvertices", np);
if (np < 3 || !getattribute("geom:polyvertices", p))
return 0.0;
}
if (raster)
{
// Project the derivatives of P to the viewing plane defined
// by I so we have a measure of how big is a pixel at this point
float pixelWidthX = length(Dx(P) - dot(Dx(P), I) * I);
float pixelWidthY = length(Dy(P) - dot(Dy(P), I) * I);
// Take the average of both axis' length
pixelWidth = (pixelWidthX + pixelWidthY) / 2;
}
// Use half the width as the neighbor face will render the
// other half. And take the square for fast comparison
pixelWidth *= 0.5 * line_width;
pixelWidth *= pixelWidth;
for (int i = 0; i < np; i++)
{
int i2 = i ? i - 1 : np - 1;
vector dir = P - p[i];
vector edge = p[i] - p[i2];
vector crs = cross(edge, dir);
// At this point dot(crs, crs) / dot(edge, edge) is
// the square of area / length(edge) == square of the
// distance to the edge.
if (dot(crs, crs) < (dot(edge, edge) * pixelWidth))
return 1;
}
return 0;
}
float wireframe(string edge_type, float line_width) { return wireframe(edge_type, line_width, 1); }
float wireframe(string edge_type) { return wireframe(edge_type, 1.0, 1); }
float wireframe() { return wireframe("polygons", 1.0, 1); }
#endif /* CCL_OSLUTIL_H */
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