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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 shader code for drawing "angle" arrow heads, which
* are drawn as two lines moving away from the arrow tip under a certain
* angle.
*/
#include "arrowheads/util.glsl"
/**
* Computes the signed distance to an angle arrow. This is a helper function,
* and in general you'll use arrow_angle_30, arrow_angle_60 or arrow_angle_90.
*
* Parameters:
* -----------
* texcoord
* Point to compute distance to
* size
* Size of the arrow head in pixels
* height
* Height of the head (pixel)
*
* See also
* --------
* arrow_angle_30, arrow_angle_60, arrow_angle_90
*
* Return:
* -------
* Signed distance to the arrow
*/
float arrow_angle(vec2 texcoord, float size,
float linewidth, float antialias, float height)
{
float d;
vec2 start = -vec2(size/2.0, 0.0);
vec2 end = +vec2(size/2.0, 0.0);
vec2 p1 = start + size*vec2(0.0, +height);
vec2 p2 = start + size*vec2(0.0, -height);
// Arrow tip (beyond segment end)
if( texcoord.x > size/2.0) {
// Head : 2 segments
float d1 = line_distance(texcoord, end, p1);
float d2 = line_distance(texcoord, p2, end);
// Body : 1 segment
float d3 = end.x - texcoord.x;
d = max(max(d1,d2), d3);
} else {
// Head : 2 segments
float d1 = segment_distance(texcoord, p1, end);
float d2 = segment_distance(texcoord, p2, end);
// Body : 1 segment
float d3 = segment_distance(texcoord, vec2(0.0, 0.0), end);
d = min(min(d1,d2), d3);
}
return d;
}
/**
* Returns the distance to an arrow with tip corner of 30 degrees
*
* See also
* --------
* arro_angle, arrow_angle_60, arrow_angle_90
*/
float arrow_angle_30(vec2 texcoord, float size,
float linewidth, float antialias)
{
return arrow_angle(texcoord, size, linewidth, antialias, 0.25);
}
/**
* Returns the distance to an arrow with tip corner of 60 degrees
*
* See also
* --------
* arro_angle, arrow_angle_30, arrow_angle_90
*/
float arrow_angle_60(vec2 texcoord, float size,
float linewidth, float antialias)
{
return arrow_angle(texcoord, size, linewidth, antialias, 0.5);
}
/**
* Returns the distance to an arrow with tip corner of 90 degrees
*
* See also
* --------
* arro_angle, arrow_angle_30, arrow_angle_60
*/
float arrow_angle_90(vec2 texcoord, float size,
float linewidth, float antialias)
{
return arrow_angle(texcoord, size, linewidth, antialias, 1.0);
}
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