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/**
* Copyright (c) Vispy Development Team
* Distributed under the (new) BSD License. See LICENSE.txt for more info.
*
* This file contains the code for drawing complete triangles as arrow heads.
* this includes triangles with a top corner of 30, 60 and 90 degrees.
*/
#include "arrowheads/util.glsl"
/**
* Computes the signed distance to a triangle arrow. This is a helper function,
* and in general you'll use arrow_triangle_30, arrow_triangle_60, or
* arrow_triangle_90.
*
* Parameters:
* -----------
*
* texcoord
* Point to compute distance to
* size
* Size of the arrow head in pixels
* linewidth
* Width of the line
* antialias
* Anti alias width
* height
* Height of the head (pixel)
*
* See also
* --------
* arrow_triangle_30, arrow_triangle_60, arrow_triangle_90
*
* Return:
* -------
* Signed distance to the arrow
*
*/
float arrow_triangle(vec2 texcoord, float size,
float linewidth, float antialias, float height)
{
vec2 start = -vec2(size/2.0, 0.0);
vec2 end = +vec2(size/2.0, 0.0);
// Head : 3 lines
vec2 p1 = start + size*vec2(0.0, +height);
vec2 p2 = start + size*vec2(0.0, -height);
float d1 = line_distance(texcoord, end, p1);
float d2 = line_distance(texcoord, p2, end);
float d3 = start.x - texcoord.x;
return max(max(d1, d2), d3);
}
/**
* Returns the signed distance to an triangle arrow head with a tip corner
* of 30 degrees.
*
* See also
* --------
* arrow_triangle, arrow_triangle_60, arrow_triangle_90
*/
float arrow_triangle_30(vec2 texcoord, float size,
float linewidth, float antialias)
{
return arrow_triangle(texcoord, size, linewidth, antialias, 0.25);
}
/**
* Returns the signed distance to an triangle arrow head with a tip corner
* of 60 degrees.
*
* See also
* --------
* arrow_triangle, arrow_triangle_30, arrow_triangle_90
*/
float arrow_triangle_60(vec2 texcoord, float size,
float linewidth, float antialias)
{
return arrow_triangle(texcoord, size, linewidth, antialias, 0.5);
}
/**
* Returns the signed distance to an triangle arrow head with a tip corner
* of 90 degrees.
*
* See also
* --------
* arrow_triangle, arrow_triangle_30, arrow_triangle_60
*/
float arrow_triangle_90(vec2 texcoord, float size,
float linewidth, float antialias)
{
return arrow_triangle(texcoord, size, linewidth, antialias, 1.0);
}
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