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uniform mat4 ProjectionMatrix;
uniform mat4 ViewMatrix;
uniform sampler2D strokeColor;
uniform sampler2D strokeDepth;
uniform vec2 Viewport;
uniform vec3 loc;
uniform int radius;
uniform float angle;
uniform int transparent;
uniform float pixsize; /* rv3d->pixsize */
uniform float pixfactor;
out vec4 FragColor;
float defaultpixsize = pixsize * (1000.0 / pixfactor);
/* project 3d point to 2d on screen space */
vec2 toScreenSpace(vec4 vertex)
{
/* need to calculate ndc because this is not done by vertex shader */
vec3 ndc = vec3(vertex).xyz / vertex.w;
vec2 sc;
sc.x = ((ndc.x + 1.0) / 2.0) * Viewport.x;
sc.y = ((ndc.y + 1.0) / 2.0) * Viewport.y;
return sc;
}
/* This swirl shader is a modified version of original Geeks3d.com code */
void main()
{
vec2 uv = vec2(gl_FragCoord.xy);
float stroke_depth;
vec4 outcolor;
vec4 center3d = ProjectionMatrix * ViewMatrix * vec4(loc.xyz, 1.0);
vec2 center = toScreenSpace(center3d);
vec2 tc = uv - center;
float dist = length(tc);
float locpixsize = abs((loc.z * defaultpixsize));
if (locpixsize == 0) {
locpixsize = 1;
}
float pxradius = (ProjectionMatrix[3][3] == 0.0) ? (radius / locpixsize) :
(radius / defaultpixsize);
pxradius = max(pxradius, 1);
if (dist <= pxradius) {
float percent = (pxradius - dist) / pxradius;
float theta = percent * percent * angle * 8.0;
float s = sin(theta);
float c = cos(theta);
tc = vec2(dot(tc, vec2(c, -s)), dot(tc, vec2(s, c)));
tc += center;
stroke_depth = texelFetch(strokeDepth, ivec2(tc), 0).r;
outcolor = texelFetch(strokeColor, ivec2(tc), 0);
}
else {
if (transparent == 1) {
discard;
}
stroke_depth = texelFetch(strokeDepth, ivec2(uv), 0).r;
outcolor = texelFetch(strokeColor, ivec2(uv), 0);
}
gl_FragDepth = stroke_depth;
FragColor = outcolor;
}
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