Fisheye & Anti fisheye Camera Effect

Usage

Add the following Nodes to your scene:

• Canvas Item / Control
  • ColorRect
    • Add a Material Shader using the code below.

Sample

This project uses this shader: github.com/rafaeldelboni/godot-top-down-camera

Credits

Ported from this shadertoy

Shader code

// Converted from https://www.shadertoy.com/view/td2GzW
shader_type canvas_item;
uniform sampler2D SCREEN_TEXTURE : hint_screen_texture, filter_linear_mipmap;

// Anti fish eye (negative amount) / fish eye (positive)
uniform float effect_amount : hint_range(-2.5, 2.5) = 1.0;

void fragment() {
	// glsl -> godot shader
	vec2 iResolution = 1.0 / SCREEN_PIXEL_SIZE;
	vec4 fragCoord = FRAGCOORD;

	//normalized coords 
	vec2 p = fragCoord.xy / iResolution.x;

	//screen proroption
	float prop = iResolution.x / iResolution.y;

	//center coords
	vec2 m = vec2(0.5, 0.5 / prop);

	//vector from center to current fragment
	vec2 d = p - m;

	// distance of pixel from center
	float r = sqrt(dot(d, d)); 

	float power = effect_amount;

	//radius of 1:1 effect
	float bind;
	
	//stick to borders
	if (power > 0.0) 
		bind = sqrt(dot(m, m));
	else {
		if (prop < 1.0) 
    		bind = m.x; 
    	else 
        	bind = m.y;
	}

	vec2 uv;
	//fisheye
	if (power > 0.0)
		uv = m + normalize(d) * tan(r * power) * bind / tan( bind * power);
	//antifisheye
	else if (power < 0.0)
		uv = m + normalize(d) * atan(r * -power * 10.0) * bind / atan(-power * bind * 10.0);
	//no effect for power = 1.0
	else
		uv = p;
    uv.y *= prop;

	vec3 col = texture(SCREEN_TEXTURE, uv).rgb;
    
	COLOR = vec4(col, 1.0);
}

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