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layout(lines) in;
layout(triangle_strip, max_vertices = 4) out;
uniform vec4 color;
uniform vec2 viewportSize;
uniform float lineWidth;
uniform bool lineSmooth = true;
#if !defined(UNIFORM)
in vec4 finalColor_g[];
#endif
#ifdef CLIP
in float clip_g[];
out float clip;
#endif
out vec4 finalColor;
noperspective out float smoothline;
#define SMOOTH_WIDTH 1.0
/* Clips point to near clip plane before perspective divide. */
vec4 clip_line_point_homogeneous_space(vec4 p, vec4 q)
{
if (p.z < -p.w) {
/* Just solves p + (q - p) * A; for A when p.z / p.w = -1.0. */
float denom = q.z - p.z + q.w - p.w;
if (denom == 0.0) {
/* No solution. */
return p;
}
float A = (-p.z - p.w) / denom;
p = p + (q - p) * A;
}
return p;
}
void do_vertex(const int i, vec4 pos, vec2 ofs)
{
#if defined(UNIFORM)
finalColor = color;
#elif defined(FLAT)
/* WATCH: Assuming last provoking vertex. */
finalColor = finalColor_g[1];
#elif defined(SMOOTH)
finalColor = finalColor_g[i];
#endif
#ifdef CLIP
clip = clip_g[i];
#endif
smoothline = (lineWidth + SMOOTH_WIDTH * float(lineSmooth)) * 0.5;
gl_Position = pos;
gl_Position.xy += ofs * pos.w;
EmitVertex();
smoothline = -(lineWidth + SMOOTH_WIDTH * float(lineSmooth)) * 0.5;
gl_Position = pos;
gl_Position.xy -= ofs * pos.w;
EmitVertex();
}
void main(void)
{
vec4 p0 = clip_line_point_homogeneous_space(gl_in[0].gl_Position, gl_in[1].gl_Position);
vec4 p1 = clip_line_point_homogeneous_space(gl_in[1].gl_Position, gl_in[0].gl_Position);
vec2 e = normalize(((p1.xy / p1.w) - (p0.xy / p0.w)) * viewportSize.xy);
#if 0 /* Hard turn when line direction changes quadrant. */
e = abs(e);
vec2 ofs = (e.x > e.y) ? vec2(0.0, 1.0 / e.x) : vec2(1.0 / e.y, 0.0);
#else /* Use perpendicular direction. */
vec2 ofs = vec2(-e.y, e.x);
#endif
ofs /= viewportSize.xy;
ofs *= lineWidth + SMOOTH_WIDTH * float(lineSmooth);
do_vertex(0, p0, ofs);
do_vertex(1, p1, ofs);
EndPrimitive();
}
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