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/**
* RGB Halftone shader for three.js.
* NOTE:
* Shape (1 = Dot, 2 = Ellipse, 3 = Line, 4 = Square)
* Blending Mode (1 = Linear, 2 = Multiply, 3 = Add, 4 = Lighter, 5 = Darker)
*/
const HalftoneShader = {
name: 'HalftoneShader',
uniforms: {
'tDiffuse': { value: null },
'shape': { value: 1 },
'radius': { value: 4 },
'rotateR': { value: Math.PI / 12 * 1 },
'rotateG': { value: Math.PI / 12 * 2 },
'rotateB': { value: Math.PI / 12 * 3 },
'scatter': { value: 0 },
'width': { value: 1 },
'height': { value: 1 },
'blending': { value: 1 },
'blendingMode': { value: 1 },
'greyscale': { value: false },
'disable': { value: false }
},
vertexShader: /* glsl */`
varying vec2 vUV;
void main() {
vUV = uv;
gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0);
}`,
fragmentShader: /* glsl */`
#define SQRT2_MINUS_ONE 0.41421356
#define SQRT2_HALF_MINUS_ONE 0.20710678
#define PI2 6.28318531
#define SHAPE_DOT 1
#define SHAPE_ELLIPSE 2
#define SHAPE_LINE 3
#define SHAPE_SQUARE 4
#define BLENDING_LINEAR 1
#define BLENDING_MULTIPLY 2
#define BLENDING_ADD 3
#define BLENDING_LIGHTER 4
#define BLENDING_DARKER 5
uniform sampler2D tDiffuse;
uniform float radius;
uniform float rotateR;
uniform float rotateG;
uniform float rotateB;
uniform float scatter;
uniform float width;
uniform float height;
uniform int shape;
uniform bool disable;
uniform float blending;
uniform int blendingMode;
varying vec2 vUV;
uniform bool greyscale;
const int samples = 8;
float blend( float a, float b, float t ) {
// linear blend
return a * ( 1.0 - t ) + b * t;
}
float hypot( float x, float y ) {
// vector magnitude
return sqrt( x * x + y * y );
}
float rand( vec2 seed ){
// get pseudo-random number
return fract( sin( dot( seed.xy, vec2( 12.9898, 78.233 ) ) ) * 43758.5453 );
}
float distanceToDotRadius( float channel, vec2 coord, vec2 normal, vec2 p, float angle, float rad_max ) {
// apply shape-specific transforms
float dist = hypot( coord.x - p.x, coord.y - p.y );
float rad = channel;
if ( shape == SHAPE_DOT ) {
rad = pow( abs( rad ), 1.125 ) * rad_max;
} else if ( shape == SHAPE_ELLIPSE ) {
rad = pow( abs( rad ), 1.125 ) * rad_max;
if ( dist != 0.0 ) {
float dot_p = abs( ( p.x - coord.x ) / dist * normal.x + ( p.y - coord.y ) / dist * normal.y );
dist = ( dist * ( 1.0 - SQRT2_HALF_MINUS_ONE ) ) + dot_p * dist * SQRT2_MINUS_ONE;
}
} else if ( shape == SHAPE_LINE ) {
rad = pow( abs( rad ), 1.5) * rad_max;
float dot_p = ( p.x - coord.x ) * normal.x + ( p.y - coord.y ) * normal.y;
dist = hypot( normal.x * dot_p, normal.y * dot_p );
} else if ( shape == SHAPE_SQUARE ) {
float theta = atan( p.y - coord.y, p.x - coord.x ) - angle;
float sin_t = abs( sin( theta ) );
float cos_t = abs( cos( theta ) );
rad = pow( abs( rad ), 1.4 );
rad = rad_max * ( rad + ( ( sin_t > cos_t ) ? rad - sin_t * rad : rad - cos_t * rad ) );
}
return rad - dist;
}
struct Cell {
// grid sample positions
vec2 normal;
vec2 p1;
vec2 p2;
vec2 p3;
vec2 p4;
float samp2;
float samp1;
float samp3;
float samp4;
};
vec4 getSample( vec2 point ) {
// multi-sampled point
vec4 tex = texture2D( tDiffuse, vec2( point.x / width, point.y / height ) );
float base = rand( vec2( floor( point.x ), floor( point.y ) ) ) * PI2;
float step = PI2 / float( samples );
float dist = radius * 0.66;
for ( int i = 0; i < samples; ++i ) {
float r = base + step * float( i );
vec2 coord = point + vec2( cos( r ) * dist, sin( r ) * dist );
tex += texture2D( tDiffuse, vec2( coord.x / width, coord.y / height ) );
}
tex /= float( samples ) + 1.0;
return tex;
}
float getDotColour( Cell c, vec2 p, int channel, float angle, float aa ) {
// get colour for given point
float dist_c_1, dist_c_2, dist_c_3, dist_c_4, res;
if ( channel == 0 ) {
c.samp1 = getSample( c.p1 ).r;
c.samp2 = getSample( c.p2 ).r;
c.samp3 = getSample( c.p3 ).r;
c.samp4 = getSample( c.p4 ).r;
} else if (channel == 1) {
c.samp1 = getSample( c.p1 ).g;
c.samp2 = getSample( c.p2 ).g;
c.samp3 = getSample( c.p3 ).g;
c.samp4 = getSample( c.p4 ).g;
} else {
c.samp1 = getSample( c.p1 ).b;
c.samp3 = getSample( c.p3 ).b;
c.samp2 = getSample( c.p2 ).b;
c.samp4 = getSample( c.p4 ).b;
}
dist_c_1 = distanceToDotRadius( c.samp1, c.p1, c.normal, p, angle, radius );
dist_c_2 = distanceToDotRadius( c.samp2, c.p2, c.normal, p, angle, radius );
dist_c_3 = distanceToDotRadius( c.samp3, c.p3, c.normal, p, angle, radius );
dist_c_4 = distanceToDotRadius( c.samp4, c.p4, c.normal, p, angle, radius );
res = ( dist_c_1 > 0.0 ) ? clamp( dist_c_1 / aa, 0.0, 1.0 ) : 0.0;
res += ( dist_c_2 > 0.0 ) ? clamp( dist_c_2 / aa, 0.0, 1.0 ) : 0.0;
res += ( dist_c_3 > 0.0 ) ? clamp( dist_c_3 / aa, 0.0, 1.0 ) : 0.0;
res += ( dist_c_4 > 0.0 ) ? clamp( dist_c_4 / aa, 0.0, 1.0 ) : 0.0;
res = clamp( res, 0.0, 1.0 );
return res;
}
Cell getReferenceCell( vec2 p, vec2 origin, float grid_angle, float step ) {
// get containing cell
Cell c;
// calc grid
vec2 n = vec2( cos( grid_angle ), sin( grid_angle ) );
float threshold = step * 0.5;
float dot_normal = n.x * ( p.x - origin.x ) + n.y * ( p.y - origin.y );
float dot_line = -n.y * ( p.x - origin.x ) + n.x * ( p.y - origin.y );
vec2 offset = vec2( n.x * dot_normal, n.y * dot_normal );
float offset_normal = mod( hypot( offset.x, offset.y ), step );
float normal_dir = ( dot_normal < 0.0 ) ? 1.0 : -1.0;
float normal_scale = ( ( offset_normal < threshold ) ? -offset_normal : step - offset_normal ) * normal_dir;
float offset_line = mod( hypot( ( p.x - offset.x ) - origin.x, ( p.y - offset.y ) - origin.y ), step );
float line_dir = ( dot_line < 0.0 ) ? 1.0 : -1.0;
float line_scale = ( ( offset_line < threshold ) ? -offset_line : step - offset_line ) * line_dir;
// get closest corner
c.normal = n;
c.p1.x = p.x - n.x * normal_scale + n.y * line_scale;
c.p1.y = p.y - n.y * normal_scale - n.x * line_scale;
// scatter
if ( scatter != 0.0 ) {
float off_mag = scatter * threshold * 0.5;
float off_angle = rand( vec2( floor( c.p1.x ), floor( c.p1.y ) ) ) * PI2;
c.p1.x += cos( off_angle ) * off_mag;
c.p1.y += sin( off_angle ) * off_mag;
}
// find corners
float normal_step = normal_dir * ( ( offset_normal < threshold ) ? step : -step );
float line_step = line_dir * ( ( offset_line < threshold ) ? step : -step );
c.p2.x = c.p1.x - n.x * normal_step;
c.p2.y = c.p1.y - n.y * normal_step;
c.p3.x = c.p1.x + n.y * line_step;
c.p3.y = c.p1.y - n.x * line_step;
c.p4.x = c.p1.x - n.x * normal_step + n.y * line_step;
c.p4.y = c.p1.y - n.y * normal_step - n.x * line_step;
return c;
}
float blendColour( float a, float b, float t ) {
// blend colours
if ( blendingMode == BLENDING_LINEAR ) {
return blend( a, b, 1.0 - t );
} else if ( blendingMode == BLENDING_ADD ) {
return blend( a, min( 1.0, a + b ), t );
} else if ( blendingMode == BLENDING_MULTIPLY ) {
return blend( a, max( 0.0, a * b ), t );
} else if ( blendingMode == BLENDING_LIGHTER ) {
return blend( a, max( a, b ), t );
} else if ( blendingMode == BLENDING_DARKER ) {
return blend( a, min( a, b ), t );
} else {
return blend( a, b, 1.0 - t );
}
}
void main() {
if ( ! disable ) {
// setup
vec2 p = vec2( vUV.x * width, vUV.y * height );
vec2 origin = vec2( 0, 0 );
float aa = ( radius < 2.5 ) ? radius * 0.5 : 1.25;
// get channel samples
Cell cell_r = getReferenceCell( p, origin, rotateR, radius );
Cell cell_g = getReferenceCell( p, origin, rotateG, radius );
Cell cell_b = getReferenceCell( p, origin, rotateB, radius );
float r = getDotColour( cell_r, p, 0, rotateR, aa );
float g = getDotColour( cell_g, p, 1, rotateG, aa );
float b = getDotColour( cell_b, p, 2, rotateB, aa );
// blend with original
vec4 colour = texture2D( tDiffuse, vUV );
r = blendColour( r, colour.r, blending );
g = blendColour( g, colour.g, blending );
b = blendColour( b, colour.b, blending );
if ( greyscale ) {
r = g = b = (r + b + g) / 3.0;
}
gl_FragColor = vec4( r, g, b, 1.0 );
} else {
gl_FragColor = texture2D( tDiffuse, vUV );
}
}`
};
export { HalftoneShader };