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# Copyright (c) 2014, Nicolas P. Rougier. All Rights Reserved.
# Distributed under the (new) BSD License.
"""Antialiasing GLSL functions."""
# -----------------------------------------------------------------------------
# Stroke
# -----------------------------------------------------------------------------
"""Compute antialiased fragment color for a stroke line.
Inputs:
- distance (float): Signed distance to border (in pixels).
Template variables:
- linewidth (float): Stroke line width (in pixels).
- antialias (float): Stroke antialiased area (in pixels).
- stroke (vec4): Stroke color.
Outputs:
- color (vec4): The final color.
"""
ANTIALIAS_STROKE = """
vec4 stroke(float distance)
{
vec4 frag_color;
float t = $linewidth/2.0 - $antialias;
float signed_distance = distance;
float border_distance = abs(signed_distance) - t;
float alpha = border_distance/$antialias;
alpha = exp(-alpha*alpha);
if( border_distance < 0.0 )
frag_color = $stroke;
else
frag_color = vec4($stroke.rgb, $stroke.a * alpha);
return frag_color;
}
"""
# -----------------------------------------------------------------------------
# Stroke
# -----------------------------------------------------------------------------
"""Compute antialiased fragment color for an outlined shape.
Inputs:
- distance (float): Signed distance to border (in pixels).
Template variables:
- linewidth (float): Stroke line width (in pixels).
- antialias (float): Stroke antialiased area (in pixels).
- stroke (vec4): Stroke color.
- fill (vec4): Fill color.
Outputs:
- color (vec4): The final color.
"""
ANTIALIAS_OUTLINE = """
vec4 outline(float distance)
{
vec4 frag_color;
float t = $linewidth/2.0 - $antialias;
float signed_distance = distance;
float border_distance = abs(signed_distance) - t;
float alpha = border_distance/$antialias;
alpha = exp(-alpha*alpha);
if( border_distance < 0.0 )
frag_color = $stroke;
else if( signed_distance < 0.0 )
frag_color = mix($fill, $stroke, sqrt(alpha));
else
frag_color = vec4($stroke.rgb, $stroke.a * alpha);
return frag_color;
}
"""
# -----------------------------------------------------------------------------
# Filled
# -----------------------------------------------------------------------------
"""Compute antialiased fragment color for a filled shape.
Inputs:
- distance (float): Signed distance to border (in pixels).
Template variables:
- linewidth (float): Stroke line width (in pixels).
- antialias (float): Stroke antialiased area (in pixels).
- fill (vec4): Fill color.
Outputs:
- color (vec4): The final color.
"""
ANTIALIAS_FILLED = """
vec4 filled(float distance)
{
vec4 frag_color;
float t = $linewidth/2.0 - $antialias;
float signed_distance = distance;
float border_distance = abs(signed_distance) - t;
float alpha = border_distance/$antialias;
alpha = exp(-alpha*alpha);
if( border_distance < 0.0 )
frag_color = $fill;
else if( signed_distance < 0.0 )
frag_color = $fill;
else
frag_color = vec4($fill.rgb, alpha * $fill.a);
return frag_color;
}
"""
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