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// ----------------------------------------------------------------------------
// Copyright (c) 2014, Nicolas P. Rougier. All Rights Reserved.
// Distributed under the (new) BSD License.
// ----------------------------------------------------------------------------
// Hooks:
// <transform> : vec4 function(position, ...)
//
// ----------------------------------------------------------------------------
#include "misc/viewport-NDC.glsl"
// Externs
// ------------------------------------
// extern vec3 prev;
// extern vec3 curr;
// extern vec3 next;
// extern float id;
// extern vec4 color;
// extern float antialias;
// extern float linewidth;
// extern vec4 viewport;
// vec4 transform(vec3 position);
// Varyings
// ------------------------------------
varying float v_antialias;
varying float v_linewidth;
varying float v_distance;
varying vec4 v_color;
// Main
// ------------------------------------
void main (void)
{
// This function is externally generated
fetch_uniforms();
v_linewidth = linewidth;
v_antialias = antialias;
v_color = color;
// transform prev/curr/next
vec4 prev_ = $transform(vec4(prev, 1));
vec4 curr_ = $transform(vec4(curr, 1));
vec4 next_ = $transform(vec4(next, 1));
// prev/curr/next in viewport coordinates
vec2 _prev = NDC_to_viewport(prev_, viewport.zw);
vec2 _curr = NDC_to_viewport(curr_, viewport.zw);
vec2 _next = NDC_to_viewport(next_, viewport.zw);
// Compute vertex final position (in viewport coordinates)
float w = linewidth/2.0 + 1.5*antialias;
float z;
vec2 P;
if( curr == prev) {
vec2 v = normalize(_next.xy - _curr.xy);
vec2 normal = normalize(vec2(-v.y,v.x));
P = _curr.xy + normal*w*id;
} else if (curr == next) {
vec2 v = normalize(_curr.xy - _prev.xy);
vec2 normal = normalize(vec2(-v.y,v.x));
P = _curr.xy + normal*w*id;
} else {
vec2 v0 = normalize(_curr.xy - _prev.xy);
vec2 v1 = normalize(_next.xy - _curr.xy);
vec2 normal = normalize(vec2(-v0.y,v0.x));
vec2 tangent = normalize(v0+v1);
vec2 miter = vec2(-tangent.y, tangent.x);
float l = abs(w / dot(miter,normal));
P = _curr.xy + miter*l*sign(id);
}
if( abs(id) > 1.5 ) v_color.a = 0.0;
v_distance = w*id;
gl_Position = viewport_to_NDC(vec3(P, curr_.z/curr_.w), viewport.zw);
}
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