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//
// Fragment shader for grid
//
// Author: Dan Gudmundsson
//
#version 120
uniform vec4 scale;
uniform vec3 color;
varying vec3 pos3d;
varying vec2 pos2d;
float grid(vec3 fragPos3D, float scale) {
vec2 coord = fragPos3D.xz * scale; // use the scale variable to set the distance between the lines
vec2 derivative = fwidth(coord);
vec2 grid = abs(fract(coord - 0.5) - 0.5) / derivative;
float line = min(grid.x, grid.y);
return 1.0 - min(line, 1.0);
}
void main(void)
{
// fade with radius from center
float fade = 1.0-min(1.0,length(pos2d));
// calc and with scale.x & y and multiply with respective alpha scale.z & w
float alpha = grid(pos3d, scale.x)*scale.z + grid(pos3d, scale.y)*scale.w;
gl_FragColor = vec4(color, alpha * fade * fade);
}
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