Why canvas item shader works a little "unpredictable"?

TTaykAH

Hello. It is worth saying that I've never worked with shaders and possibly don't familiar with some base concepts. So my purpose is writing simple outline shader, no more, and I don't see the point in spending a lot of time to learn shading skills.

All magenta pixels actually transparent, magenta only here for visibility on white background.

So I have some sprite and outline mask sprite with same size. In shader I want impose outline mask to sprite to get outline effect. Probably sounds unclear, let's go to specific sprites. I have this spritesheet with isometric-ship: And this outline mask: In sprite node first set as texture, second as normal map: I've created new matireal, and put this code in shader script:

shader_type canvas_item;

void fragment(){
	COLOR = texture(TEXTURE, UV)+texture(NORMAL_TEXTURE, UV);
}

In my mind, empty pixels from NORMAL_TEXTURE added with colored pixels from TEXTURE should save color from TEXTURE in the result. But I see that: So just overlaying outline mask to sprite in any graphic editor have another result: At first I thought about non-zero values in rbg channels, and we don't see color becouse alpha channel set as0, but when adding two textures in shader script they make themselves felt. So I filled whole transparent pixels in black, and now outline mask looks like this: But in godot result more strange: I tryied all render_mode, but the result did't suit me. And now I understand that I need forum help.

Thanks that you read this considerable question, I tried told you everything I had tried or thought. I hope you haven't questions to my question :)

TwistedTwigleg

Maybe try this with the black mask:

shader_type canvas_item;
void fragment(){
    vec4 mask_col = texture(NORMAL_TEXTURE, UV);
    if (mask_col.r > 0.1) {
        COLOR = mask_col;
    }
    else {
        COLOR = texture(TEXTURE, UV);
    }
}

Megalomaniak

That looks like you might have exported an 'optimized' PNG? What image editor are you exporting from, and with what settings? And what are your image import settings in godot?

TTaykAH

@TwistedTwigleg your example should work and I'd been even using this method. But I refused from It becouse this doesn't allow using transparent, or modulated outline color. I thought about outline mask as place where outline must be, and about every pixel settings, like modulating outline color, or transparent. For example I have white pixel with alpha channel as 0.2 which overlaps colored pixel from sprite, so this pixel must lighten up a little, but in your example this pixel just replace colored pixel and there will be "white hole" in result render.

TTaykAH

@Megalomaniak I use Aseprite v1.2.9-x64, export settings in aseprite and import settings in godot you can see on screenshots:

edited: Also I tried .bmp format, with a little another code in shader:

shader_type canvas_item;

void fragment(){
	COLOR = vec4(texture(TEXTURE, UV).rgb+texture(NORMAL_TEXTURE, UV).rgb, 1.0);
}

And finally right result: So that your assumption must be right. But I still didn't reach the same result with .png format, I've re-exported this sprite with gimp without compression, and file size increased to ~75 KB against ~9 KB with aseprite, but result haven't changed.

TTaykAH

heheheh. This problem fixes with just switching off Fix Alpha Border setting in import settings. In godot docs I don't quite understand what's It doing, but now it does not matter)