Transparency and DrawingSurface

[Gurok]

Hello,

I am trying to draw this simple graphic onto a GUI:



It's a partially transparent smiley face. The actual graphic is 16x16, but I've resized it for readability.

My game is a 32-bit colour game. I used the default game and made a new GUI called gTest. I imported the sprite and used its alpha channel. I changed Roger's interact function to:

Code: ags

DynamicSprite *mySprite;

function cEgo_Interact()
{
	DrawingSurface *out;

	if(mySprite != null)
		mySprite.Delete();
	mySprite = DynamicSprite.Create(16, 16, true);
	out = mySprite.GetDrawingSurface();
	out.DrawImage(0, 0, 6);
	out.Release();
	gTest.BackgroundGraphic = mySprite.Graphic;
	gTest.Width = 16;
	gTest.Height = 16;
	gTest.X = 50;
	gTest.Y = 50;
	gTest.Visible = true;
}

Here is what I see when I interact with Roger:



Transparent pixels where semi-opaque ones should be and opaque pixels remain where transparent ones are.

I've read some of the articles about AGS and blending and I appreciate that things are a little wonky when it comes to transparency in AGS. I'm not asking AGS to blend the sprite here. I just want it to set the alpha to a non-zero value for semi-transparent areas. Here's what I'd expect to see instead:



I would then be able to happily turn off the border/background and have a semi-transparent GUI.

I have tried playing around with various parameters to the functions. About the only thing that seems to make a difference is toggling transparency on the surface. If I set it to false, I get the classic purple blending going on:



I guess this proves that AGS is seeing my image has non-zero alpha in those areas, but not much else.

Please help me figure this out, guys. What do I need to do to draw this correctly on a DynamicSprite? If you want to try to replicate this, here's what I did:

1. Create a new default game
2. Set the colour depth to 32-bit
3. Add a new GUI called gTest
4. Import this sprite (here's the exact sprite: ) as sprite number 6
5. Replace Roger's interaction with the code above
6. Run the game and interact with Roger

Note: I am running 3.3.0 Beta 12.

[Crimson Wizard]

Default game template still uses old (improper) alpha blending. Good you noticed this, needs to be fixed.

Go to General Settings and set "Visual"->"Sprite alpha rendering style" to "Proper Alpha Blending".
Also probably is a good idea to set "Visual"->"GUI alpha rendering style" to "Multiplied Translucence..." (because it is proper alpha blending too).

[Gurok]

Thanks CW! I was tearing my hair out trying to find the right option.

[Monsieur OUXX]

Go to General Settings and set "Visual"->"Sprite alpha rendering style" to "Proper Alpha Blending".
Also probably is a good idea to set "Visual"->"GUI alpha rendering style" to "Multiplied Translucence..."

WOW it's a good thing I read this thread, I didn't know the transparency fixes had been introduced that way. I definitely learnt something very useful here!

[Crimson Wizard]

WOW it's a good thing I read this thread, I didn't know the transparency fixes had been introduced that way.

This is done for backwards-compatibility (in case you import older project and want it retain all the behavior).
In most cases there should not be a reason to use other modes than "proper" ones.

We need to fix the templates that come with 3.3.0 to have this by default. At least "Empty" and "Default" templates.