[2D] Sparkling star effect ver 2.1

。Opening

It is a sparkling star effect.

一個閃爍旋轉星星

。Change Log

-ver 2.1 add

Change method for cut_radius to decay_magnitude and cut_magnitude.

-ver 2.1 更新

改變算法，uniform 由 cut_radius 改成 decay_magnitude 和 cut_magnitude。

Shader code

shader_type canvas_item;

uniform vec4 color :source_color = vec4(1.,1.,1.,1.);
uniform float scale : hint_range(0.1, 10000.0, 0.1) = 7500;
uniform float circle_ratio: hint_range(0.0, 100.0, 0.1) = 0.;
uniform float decay_magnitude: hint_range(0.0, 1.0, 0.01) = 0.1;
uniform float cut_magnitude: hint_range(0.0, 1.0, 0.01) = 0.05;
uniform float rotate_speed: hint_range(-1000, 1000, 0.01) = 1;
uniform float time_speed: hint_range(-1000, 1000, 0.01) = 1;

uniform float frequency_base: hint_range(0.0, 10.0, 0.01) = 1.;
uniform float frequency_disturbance_scale: hint_range(0.0, 10.0, 0.01) = 0.;

uniform bool stop_shine = false;

float onedx(float x) {

	if (x + 1. - 1. == 0.) {

		return 1.;
	} else {

		return 1./x;
	}
}

float onedx2(float x) {

	return  onedx(x)*onedx(x);
}

float getBetaW(float x, float f, float size) {

	return size*x*3.1415926/f;
}

float getBetaH(float y, float f, float size) {

	return size*y*3.1415926/f;
}

float getI(vec2 uv, float f, vec2 SIZE) {
    
	return onedx2(getBetaW(uv.x, f, SIZE.x))*onedx2(getBetaH(uv.y, f, SIZE.y));
}

vec2 rotate(vec2 uv, float addtheta) {

    float theta = atan(uv.y/uv.x) + addtheta;
    float r = sqrt(uv.x*uv.x + uv.y*uv.y);
    vec2 ruv;
	ruv.x = r*cos(theta);
    ruv.y = r*sin(theta);
        
    return ruv;
}

void fragment() {
    
    vec2 st = rotate((UV - 0.5)*scale, TIME*rotate_speed);
	float r = sqrt(st.x*st.x + st.y*st.y);
    st = st*pow(r, circle_ratio);

    float time = TIME*time_speed;

    float f = frequency_base + frequency_disturbance_scale*(3.*sin(time) + 2.*cos(time*4.) + 6.*sin(time*2.) + 1.*sin(time*3.));
    float L = distance(UV,st);
	float M = exp(-L*L*decay_magnitude*decay_magnitude/scale);

	M = M < 0.05 ? 0. : M;
    
	f = stop_shine ? frequency_base : f;

	COLOR = vec4(min(vec3(getI(st, f, SCREEN_PIXEL_SIZE))*M, 1.),1.0)*color;
}

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