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glslgodotgodot-shader-language

Why does my shader work fine in the Godot editor, but not in runtime?

I wrote a shader on a CanvasItem in Godot:

shader_type canvas_item;

void fragment() {
    vec2 distortedUV = UV;
    distortedUV.x += sin(distortedUV.y * 5.0 * TIME/100.0 + TIME) * 0.1;
    COLOR = texture(TEXTURE, distortedUV);
}

In the editor it looks like this:

editor shader pic

However when I run the game, it just slowly moves back and forth with little amplitude and looks like this:

runtime image

Why is this? Some more information about my settings: This is on a TextureRect that is a child of a Control node. It is a pixel game so setup as such. The window is 360x640 and scaled up to 720x1280 during runtime. Use GPU pixel snap == true. The sprite is a .png imported with the 2D Pixel texture preset.

Solution

  • Likely the engine was running for a while, and so it has values of TIME bigger than those observed in the game when launching it for testing.

    So, in the game, you have a small value of TIME, but in the engine you - probably - had a big value of TIME.

    Now consider the effect of a small value of TIME in this expression:

    distortedUV.y * 5.0 * TIME/100.0 + TIME

    The value of TIME/100.0 becomes near zero. So distortedUV.y * 5.0 * TIME/100.0 becomes near zero, and thus the effect of the vertical coordinate of distortedUV becomes negligible.