How to change RGB Coefficient at runtime?

[Outcast]

I am trying to change the colour of a white box so it blends into different colours, it might go from red to gren and then to yellow and blend back to another colour etc etc etc. But I have not found a way to easely do it. Do anyone know how to do this? If I just try to use the action set RGB coefficient I don't get the intended result so I must be missing something.

[piscesdreams]

You can set the RGB coefficient under the active object, then get the RGB values using the Special "GetRGB" action. It allows you to isolate the R,G and B values separately. I find it's best to use dedicated alterable values for each of the RGB values.

[Volnaiskra]

It can take a bit of trial and error to get the color you want, as the RGB tends to work differently to how you're probably used to it. It tends to be a 'subtractive' process. All graphics have a RGB of 255,255,255 by default, even when they're not all white (as most graphics aren't, of course). To get them to tint a color that you want, you then need to subtract from 255. So if you want something to go red, you can't just add red, since red is already at 255 (the max). So you instead have to subtract green and blue. How much you need to subtract them will depend on how much green and blue there is in the source active: eg. if your active has lots of purple in it, then you might need to subtract lots of blue but only a little green.

Though in your current case you just have a white box, so that should make it easier. Just remember that you'll often be subracting, not adding. Don't make the mistake of thinking 'oh, I'll just add a bit of red, so I'll try SetRGB to GetRGB(100,0,0), as that will probably make your result too dark, since you've not only stripped all blue and green, but also stripped most of the red (from 255 down to 100). So instead try something like SetRGB to GetRGB(255,50,50)

[BartekB]

Like Volnaiskra said, but personally I like to think of the RGB coefficient as a multiply layer filled with a solid colour (that you pass in) above the sprite, like you could do in Photoshop.
To cycle through colours/hue, it'd be best to do this in HSV (Hue, Saturation, Value) rather than RGB (Red, Green, Blue) as it is more intuitive for humans as well as makes hue cycling as trivial as always adding 1 to a variable.

The attached example does just that, and includes a HSV -> RGB converter: HueShift_HSV_RGB.mfa

[Volnaiskra]

.........includes a HSV -> RGB converter...

Woohoo! Thanks for sharing this. It'll come in useful for me for sure!

There's no possible way to make a pixel brighter than its original using the SetRGB method, is there? Like you say, it seems like using Multiply in Photoshop, where you can make various pixels a bit darker, a lot darker, or unchanged, but never brighter.

Or, to put it a different way, there's no limit to how much SetRGB can change a pure white pixel, whereas SetRGB can't make any change at all to an already black pixel. Is that correct?

[BartekB]

That's correct, with the RGB coefficient it is not possible to get a brighter result because colour works in a 0.0 to 1.0 range.
and when you multiply something with 1.0 (white coefficient), you get the same original thing back, but multiply something with 0.0 (black coefficient) and you get 0.0 (black).

[Dobermann]

Didn't knew that GetRGB function exists... There so much things that are hard to find in Fusion...

I'd created a simple formula to use it:

Set RGB coefficient to Red Value + ( Green Value * 256 ) + ( Blue Value * 65536 )

[Outcast]

Hmm I am stuck at the GetRGB action. I just grab it from my active (at pixel 30,30 though I dont think that matters), but I always get the same number 15793151 no matter what RGB coefficient I have set it to in the frame?

I did manage to change the hue though by just increasing the rgb value at runtime, but only in bluish color and it "snaps" at a point and resets. I want to have the white box go from blue, to green to red etc etc (not in that particular order) and always changing. No idea how the logic behind all this works now though

Any ideas?

HugeChange.mfa

[BartekB]

Hmm I am stuck at the GetRGB action. I just grab it from my active (at pixel 30,30 though I dont think that matters), but I always get the same number 15793151 no matter what RGB coefficient I have set it to in the frame?

I did manage to change the hue though by just increasing the rgb value at runtime, but only in bluish color and it "snaps" at a point and resets. I want to have the white box go from blue, to green to red etc etc (not in that particular order) and always changing. No idea how the logic behind all this works now though

Any ideas?

HugeChange.mfa

You shouldn't ever add/subtract to the RGB coefficient directly. Because RGB coefficient is an integer holding 3 values.

See Dobermann's expression:

I'd created a simple formula to use it:
Set RGB coefficient to Red Value + ( Green Value * 256 ) + ( Blue Value * 65536 )

This is what "RGB coefficient" is equal to. For reverse, the expression would be:
Red = RGB mod 256
Green = (RGB / 256) mod 256
Blue = (RGB / 65536) mod 256

By adding 1 to RGB coefficient, you're adding 1 to Red. If Red exceeds 255, Red is reset back to 0 and 1 is added to Green. This is what causes that "snap"

You always get 15793151 because RGBAt retrieves original colour from the sprite, not colour that was applied with RGB coefficient.

Look at my previous example that I have posted here with the hue change, it's not as simple as adding 1: HueShift_HSV_RGB.mfa
Edit: You're also using RGBAt, nowhere in the file was GetRGB used, they're two different expressions. The latter "makes" the integer value RGB coefficient uses (easy solution to not deal with writing the expression Dobermann wrote above)

[Volnaiskra]

Didn't knew that GetRGB function exists... There so much things that are hard to find in Fusion...

True. It feels almost like a puzzle mini-game to figure out how to change a hotkey, for example

But to be fair, when it comes to actions/conditions/expressions, most of the hard-to-find things are actually all in one spot - the Special Object (well, 3 spots I guess, since it exists in action, condition, and expression forms). Here's GetRGB:



I've learnt to peruse the Special Object from time to time, to be reminded of what things are available. There are a lot of functions crammed into that one object, but they're all there categorised in the drop menus.