Hull heating shader effect

[fluffyfreak]

Description:

Apply a simple heating shader effect based on the hull temperature and direction of travel.

It adds one texture which controls the heat gradient coloring. If you want to make it fade in later than squash the gradient further up and extand the black section towards the middle. Vice versa with the white end if you want it to ramp up earlier.

@shadmar you're a shader Ninja :) any advice on the shader itself?

Testing:

The best way to test is to launch with a powerful ship like the PumpkinSeed and make sure it hasn't got any atmospheric shielding. It's pretty clear when it's getting toasty!

Andy

@robn / @johnbartholomew - this is no longer WIP so is ready for review whenever there's opportunity. Check it out as it's quite a nice effect I think :) Wish I'd done it sooner!

[nozmajner]

Neat!
Could it be possible to have arbitrary parts that start to glow when there's heat? I'm thinking mainly about my grated heat sinks really. :)

[fluffyfreak]

@nozmajner Not with this one, this commit is just for heating due to being slammed through an atmosphere.
However that would be fairly easy to do, probably just with a texture which define a heat-map which matched up with the heat sinks on the ships regular texture :)

[fluffyfreak]

Instead of having the parameters be a member of each instance of a ship I've just made them a class static. I have to change and set the value for each ship anyway so it makes no discernable difference.

[shadmar]

Cool, I will look!

[fluffyfreak]

Hmm, this still needs some work.
I figured out a few things this morning, like moving the heatGradient setup out of the Loader and into Ship where I'm already playing around with the materials. Now however I appear to be having trouble with the velocity direction calculation. Still working on it :) (since 6am!)

[shadmar]

I think s_heatGradientParams.heatingNormal = vector3f(GetVelocity().Normalized() in ship.cpp needs some sort of transformation from worldspace to lightspace coordinates so the shader can take velocity vector as a lightsource direction. But I dont know how it should be done.

[fluffyfreak]

I'm wondering if I'm actually passing through the direction correctly but I need to figure it out :)

[fluffyfreak]

@shadmar tada! it seems to work for me now :)
I was transforming it incorrectly, now I'm building my own transformation matrix and multiplying it by that.

[shadmar]

oO, I used 3 hours yesterday scratching my everything, even found my matrices book.

I will have a look :)

[shadmar]

Nice! works very well, I changed one line to produce the effect earlier abit earlier so atmosphere shielded ships also get a nice effect.

vec4 heatColour = texture2D(heatGradient, vec2(pow(heatDot,0.6), 0.5)); //heat gradient blend

[shadmar]

Some of this code might be useful and could be recycled for an shield directional impact also later on (both heat and hits)

[fluffyfreak]

The shield already has a simple directional hit effect. Open a ship like the deneb (on the Shields branch) in the modelviewer and click the "Hit me!" button to see it in action :)

[fluffyfreak]

RE: vec4 heatColour = texture2D(heatGradient, vec2(pow(heatDot,0.6), 0.5)); //heat gradient blend
@shadmar could the same effect be achieved just by editing the heat gradient texture map?
I already scaled the gradient effect to occur "earlier" and mean that the entire top half of the texture effect is pure white. The idea with the atmospheric shielding is that you wouldn't really see it so much but if someone wanted to edit the effect then they can just by changing the texture rather than having to know how to edit the shader.

[shadmar]

could the same effect be achieved just by editing the heat gradient texture map?
Yeah that would be simpler :)

[jmf]

I just tested the newest version and I took that screenshot:

The yellow parts look a bit strange, also I think it could be a bit less red but more orange.
In kerbal space program the re-entry is very spectacular, look at this reference:

[fluffyfreak]

Yep and it's pretty looking. Wanna code it? ;)

I kinda know how to do it, but we have the slight problem that you can enter atmosphere facing any orientation. That means the profile from which you extend the heat shock geometry from changes as your orientation does. I don't know how to resolve that.

This is just being a step in the right direction rather than the best-ever-re-entry-effect :)

[fluffyfreak]

Actually if you can think of any way to do it then let me know and I'll try to implement it.

[johnbartholomew]

If you want to do it with a mesh like that then it looks very closely related to shadow volumes, so descriptions you can find of how to construct the geometry for a shadow volume should be applicable to this. I've never implemented shadow volumes myself; I'm not sure how difficult it is to generate them robustly.

If we had a worthwhile particle system implementation then we might be able to use that instead, although you still have to decide where to emit the particles... perhaps just put them on the 'leading' end of an ellipsoid around the ship. It wouldn't look the same, but it might look just as good with the right particle sprite(s) and parameters.

[fluffyfreak]

@johnbartholomew good point, lets move this to the dev forum though, even if find time to do something for it I don't want it to impact this PR.

[fluffyfreak]

Updated to master

[robn]

Good work on this one. Probably not perfect yet but a great start!

Produces some interesting effects with concave surfaces:

[impaktor]

Looks very nice. Would be suitable to show off on http://pioneerspacesim.net/

[fluffyfreak]

Yeah, it's very much a start rather than an end :)