110 lines
3.2 KiB
GLSL
110 lines
3.2 KiB
GLSL
/*
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* This program source code file is part of KICAD, a free EDA CAD application.
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*
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* Copyright (C) 2013-2016 CERN
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* Copyright (C) 2016 Kicad Developers, see authors.txt for contributors.
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* @author Maciej Suminski <maciej.suminski@cern.ch>
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*
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* Fragment shader
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, you may find one here:
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* http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
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* or you may search the http://www.gnu.org website for the version 2 license,
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* or you may write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
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*/
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#version 120
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// Multi-channel signed distance field
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#define USE_MSDF
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// Shader types
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const float SHADER_LINE = 1.0;
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const float SHADER_FILLED_CIRCLE = 2.0;
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const float SHADER_STROKED_CIRCLE = 3.0;
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const float SHADER_FONT = 4.0;
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varying vec4 shaderParams;
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varying vec2 circleCoords;
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uniform sampler2D fontTexture;
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// Needed to reconstruct the mipmap level / texel derivative
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uniform int fontTextureWidth;
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void filledCircle( vec2 aCoord )
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{
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if( dot( aCoord, aCoord ) < 1.0 )
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gl_FragColor = gl_Color;
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else
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discard;
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}
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void strokedCircle( vec2 aCoord, float aRadius, float aWidth )
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{
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float outerRadius = aRadius + ( aWidth / 2 );
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float innerRadius = aRadius - ( aWidth / 2 );
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float relWidth = innerRadius / outerRadius;
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if( ( dot( aCoord, aCoord ) < 1.0 ) &&
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( dot( aCoord, aCoord ) > relWidth * relWidth ) )
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gl_FragColor = gl_Color;
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else
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discard;
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}
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#ifdef USE_MSDF
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float median( vec3 v )
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{
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return max( min( v.r, v.g ), min( max( v.r, v.g ), v.b ) );
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}
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#endif
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void main()
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{
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if( shaderParams[0] == SHADER_FILLED_CIRCLE )
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{
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filledCircle( circleCoords );
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}
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else if( shaderParams[0] == SHADER_STROKED_CIRCLE )
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{
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strokedCircle( circleCoords, shaderParams[2], shaderParams[3] );
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}
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else if( shaderParams[0] == SHADER_FONT )
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{
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vec2 tex = shaderParams.yz;
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// Unless we're streching chars it is okay to consider
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// one derivative for filtering
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float derivative = length( dFdx( tex ) ) * fontTextureWidth / 4;
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#ifdef USE_MSDF
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float dist = median( texture2D( fontTexture, tex ).rgb );
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#else
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float dist = texture2D( fontTexture, tex ).r;
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#endif
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// use the derivative for zoom-adaptive filtering
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float alpha = smoothstep( 0.5 - derivative, 0.5 + derivative, dist );
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gl_FragColor = vec4( gl_Color.rgb, alpha );
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}
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else
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{
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// Simple pass-through
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gl_FragColor = gl_Color;
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}
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}
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