Shining Sprite Effect

This shader has to be applied directly on a sprite. It will animate depending on the TIME and use the luminance to determine which part of the sprite to highlight.

Shader code

shader_type canvas_item;

const float PI = 3.141516;

uniform float speed = 1.;

uniform vec4 tint : hint_color = vec4(1., 1., 0., 1.);

uniform float span : hint_range(0.1, 1.) = .3;

float luminance(vec4 colour) {
	return 1.0 - sqrt(0.299*colour.r*colour.r + 0.587*colour.g*colour.g + 0.114*colour.b*colour.b);
}

void fragment() {
	vec4 colour = texture(TEXTURE, UV);
	float target = abs(sin(TIME * PI * speed) * (1. + span));
	if(colour.a > 0.) {
		float lum = luminance(colour);
		float diff = abs(lum - target);
		float mx = clamp(1. - diff / span, 0., 1.);
		colour = mix(colour, tint, mx);
	}
	
	COLOR = colour;
}

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