Question about effects / blend types |
The BitmapEffects_XXX.txt files reference several different blending types which are used when drawing the effects:
Blend_Zero
Blend_One
Blend_SrcColor
Blend_InvSrcColor
etc...
How do these work? Is this information documented anywhere? I found in SE5_Modding.pdf where the various blend types are listed, but I have no idea what they do, and I can't seem to find that information.
Re: Question about effects / blend types
I suppose that this is pretty much the direct technical specification.
http://msdn2.microsoft.com/en-us/library/bb173417.aspx
And this article might help you understand how it kinda works.
http://blogs.msdn.com/etayrien/archive/2006/12/07/alpha-blending-part-1.aspx
Re: Question about effects / blend types
Thanks, Maanahr! I strongly suspected that it had something to do with Direct3D stuff. After reading that article everything makes sense.
I think I'll type up a non-technical translation for the wiki soon.
Re: Question about effects / blend types
As I understand it, you can ignore any with Alpha in the name, since Space Empires uses .bmp's, which don't have an Alpha channel. That leaves Zero, One, and the Colors.
...but I might be wrong.
Re: Question about effects / blend types
I played around with the different effects and couldn't see a difference. either I wasn't being observant enough (very possible), or at the size that everything is zoomed out, you can't see the difference.
SEV, more than a feeling.
Preview tool
Based on the information in that article, I created a simple tool which can preview the effects. In most cases the difference between blend types is subtle.
You can download the tool here:
http://www.vzavenue.net/~rogercnorris/SE5_Blend_Effects.zip
This tool requires the .NET framework v2.0 (if you get a message at startup about a missing DLL then you need to download .NET from Microsoft). You must have SE5 installed to use it.
What does it do? You select a source image, a destination image, and the blend effects to use. It displays the blended image. It may run a little slowly on older computers... I was optimizing for programmer efficiency instead of runtime speed 
Re: Question about effects / blend types
They are not really documented anywhere, unfortunately. The best suggestion I can make is find instances of each usage in BitmapEffects_System.txt and XFileClasses_Stellar.txt, change to another setting, and see what the resulting effects look like. For example, Blend_One is used for star glows, and Blend_SrcColor and Blend_InvColor are used on storm clouds. Feel free to post your discoveries here and/or add them to the Wiki.
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