不用编程的Visual Shader

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vec2 modulo(vec2 divident, vec2 divisor){
	vec2 positiveDivident = mod(divident, divisor) + divisor;
	return mod(positiveDivident, divisor);
}

vec2 random(vec2 value){
	value = vec2( dot(value, vec2(127.2,311.7) ),
				  dot(value, vec2(269.5,183.3) ) );
	return -1.0 + 2.0 * fract(sin(value) * 43758.5453123);
}

float seamless_noise(vec2 uv, float s) {
	uv = uv * s;
	vec2 cellsMinimum = floor(uv);
	vec2 cellsMaximum = ceil(uv);
	vec2 uv_fract = fract(uv);
	
	cellsMinimum = modulo(cellsMinimum, vec2(s));
	cellsMaximum = modulo(cellsMaximum, vec2(s));
	
	vec2 blur = smoothstep(0.0, 1.0, uv_fract);
	
	vec2 lowerLeftDirection = random(vec2(cellsMinimum.x, cellsMinimum.y));
	vec2 lowerRightDirection = random(vec2(cellsMaximum.x, cellsMinimum.y));
	vec2 upperLeftDirection = random(vec2(cellsMinimum.x, cellsMaximum.y));
	vec2 upperRightDirection = random(vec2(cellsMaximum.x, cellsMaximum.y));
	
	vec2 fraction = fract(uv);
	
	return clamp(mix( mix( dot( lowerLeftDirection, fraction - vec2(0, 0) ),
                     dot( lowerRightDirection, fraction - vec2(1, 0) ), blur.x),
                mix( dot( upperLeftDirection, fraction - vec2(0, 1) ),
                     dot( upperRightDirection, fraction - vec2(1, 1) ), blur.x), blur.y) * 0.8 + 0.5, 0, 1);
}