Shader won't work during runtime

[NoodleMeanie]

Godot Version

4.2

Question

Hi everyone! In my godot game I have a shader that replaces the colors of the players sprite. It works in the editor but not during runtime. I don’t know why or if it’s because of 4.2.

Here is the shader code.

shader_type canvas_item;

uniform vec4 og_color : source_color;
uniform vec4 new_color : source_color;

uniform vec4 bright_color : source_color;
uniform vec4 new_bright : source_color;

void fragment() {
	vec4 curr_color = texture(TEXTURE, UV);

    // Define a threshold for the comparison
	if (COLOR == og_color){
		COLOR = new_color;
	}
	
	if (COLOR == bright_color){
		COLOR = new_bright;
	}
	
}
	

Thank you!

[zdrmlpzdrmlp]

this looks simple enough, it basically replaces the color from specified uniform parameter, are you sure the color parameters have already changed during runtime? check the remote tab?

[NoodleMeanie]

So, the shader works in the editor, but it doesn’t work during runtime, and nothing comes up in the remote tab.

[Calinou]

This is because you’re performing floating-point comparison with exact values, which will break unexpectedly due to floating-point precision errors (just like in GDScript or C#). You need to introduce an epsilon value (here, 0.001) and check whether the value is within the range of this epsilon:

if (
    curr_color.r >= oldColor.r - 0.001 && curr_color.r <= oldColor.r + 0.001 &&
    curr_color.g >= oldColor.g - 0.001 && curr_color.g <= oldColor.g + 0.001 &&
    curr_color.b >= oldColor.b - 0.001 && curr_color.b <= oldColor.b + 0.001 && 
    curr_color.a >= oldColor.a - 0.001 && curr_color.a <= oldColor.a + 0.001
) {
    // Colors are approximately equal.
}

You can see more information about this here: Add `is_equal_approx()` and `is_zero_approx()` functions to the shader language · Issue #6870 · godotengine/godot-proposals · GitHub

[NoodleMeanie]

Thanks!