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86 lines
2.6 KiB
GLSL
86 lines
2.6 KiB
GLSL
/*
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Part of the Processing project - http://processing.org
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Copyright (c) 2011-13 Ben Fry and Casey Reas
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License version 2.1 as published by the Free Software Foundation.
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This library 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 GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General
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Public License along with this library; if not, write to the
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Free Software Foundation, Inc., 59 Temple Place, Suite 330,
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Boston, MA 02111-1307 USA
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*/
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#define PROCESSING_LINE_SHADER
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uniform mat4 modelviewMatrix;
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uniform mat4 projectionMatrix;
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uniform vec4 viewport;
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uniform int perspective;
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uniform vec3 scale;
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attribute vec4 position;
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attribute vec4 color;
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attribute vec4 direction;
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varying vec4 vertColor;
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vec3 clipToWindow(vec4 clip, vec4 viewport) {
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vec3 post_div = clip.xyz / clip.w;
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vec2 xypos = (post_div.xy + vec2(1.0, 1.0)) * 0.5 * viewport.zw;
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return vec3(xypos, post_div.z * 0.5 + 0.5);
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}
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vec4 windowToClipVector(vec2 window, vec4 viewport, float clip_w) {
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vec2 xypos = (window / viewport.zw) * 2.0;
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return vec4(xypos, 0.0, 0.0) * clip_w;
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}
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void main() {
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vec4 posp = modelviewMatrix * position;
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// Moving vertices slightly toward the camera
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// to avoid depth-fighting with the fill triangles.
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// Discussed here:
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// http://www.opengl.org/discussion_boards/ubbthreads.php?ubb=showflat&Number=252848
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posp.xyz = posp.xyz * scale;
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vec4 clipp = projectionMatrix * posp;
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float thickness = direction.w;
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if (thickness != 0.0) {
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vec4 posq = posp + modelviewMatrix * vec4(direction.xyz, 0);
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posq.xyz = posq.xyz * scale;
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vec4 clipq = projectionMatrix * posq;
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vec3 window_p = clipToWindow(clipp, viewport);
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vec3 window_q = clipToWindow(clipq, viewport);
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vec3 tangent = window_q - window_p;
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vec2 perp = normalize(vec2(-tangent.y, tangent.x));
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vec2 offset = perp * thickness;
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if (0 < perspective) {
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// Perspective correction (lines will look thiner as they move away
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// from the view position).
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gl_Position.xy = clipp.xy + offset.xy;
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gl_Position.zw = clipp.zw;
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} else {
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// No perspective correction.
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vec4 offsetp = windowToClipVector(offset, viewport, clipp.w);
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gl_Position = clipp + offsetp;
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}
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} else {
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gl_Position = clipp;
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}
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vertColor = color;
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}
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