How to make a shader for invisible objects to visible in some spots?

Question

Hello. I want to create invisible object that will turn visible on the spots where the player is close to, like in the image.
How can I achieve this? Doesn't need to be anything fancy.

Youngman

Answer 1

Using a combination of both, I have figured it out.
The only thing to note is that player_pos has to be updated constantly in gdscript.

Shader code:

shader_type spatial;


uniform vec4 _color : hint_color = vec4( 0.2, 1.0, 1.0, 1.0 );
uniform float sphere_size = 3.0;
uniform vec3 player_pos = vec3( 0.0, 0.0, 0.0 );

varying vec3 world_vertex;



void vertex( )
{
	world_vertex = (WORLD_MATRIX * vec4(VERTEX, 1.0)).xyz;
}


void fragment( )
{
	
	float min_dist = min(
		length( player_pos - world_vertex ), 10);
	
	
	ALBEDO = _color.rgb;
	ALPHA = clamp(_color.a * sphere_size - min_dist, 0.0, 1.0 );
}

Youngman

Answer 2

You can do that with a shader.

The easiest way to start is to pass the player position into the shader as a uniform vec3.

Then in the spatial material, you can create a sort of sphere in code that affects the visibility.

For example:

uniform vec3 player_position;

void fragment() {
    if (distance(player_position, pixel_position) < 10.0) {
        ALBEDO = vec3(0.0, 0.0, 1.0);
    } else {
        ALPHA_SCISSOR = 0.5
        ALPHA = 0.0
    }
}

You will just have to calculate pixel_position yourself, as that is not a built-in value, I just made it up.

But there are equations to calculate the world space position of a pixel giving the screen 2D pixel value and the depth value.

Tumulus

Answer 3

It's not exactly what you are looking for but the building blocks for what you likely want to achieve are in there:
https://godotshaders.com/shader/procedural-hex-barrier-shader/

Spell

Answer 4

The only thing to note is that player_pos has to be updated constantly in gdscript.

Yes, I didn't think to mention it since I thought it obvious enough. I assume same was the case with 's post.

Spell

Answer 5

I have another questions.
How do I make the shader effect the material/shader underneath?

I want to make the invisible shader work for various textures,
but I don't want to make a 100 versions to accommodate for those different textures.

Youngman