UE4 again.

So here's that first test I mentioned before, simply captured with fraps. It was easy after all.

Nothing ground breaking, this still just a test but I'm glad it can work the way I imagined it would.

UE 4!

I finally got myself a copy of unreal 4.
There are a lot of things I want to test but my main goal was to see if I could make an animated version of my drawings.

This is a first test after a few hours of work. Very early but promising, I think I'll be able to achieve what I have in mind.

Yeah, it's a screenshot. So much for an ‘animated’ version. I'll also have to find a method for capturing editor stuff …

Still alive.

It's been a while and I've got 3 more examples about mapping a texture to world coordinates almost ready, but these days I'm very busy with some other project of mine.

I also draw (on paper, yes, Sir) and I'm preparing my first exhibition.

Happy scientific accident.

I was in photoshop and intending to use the gradient map. (Image > Adjustment > Gradient Map)

I accidentally clicked an existing saved gradient and realized I had made sort of a scientific texture.

You know, like that sort of stuff:

 Here's my photoshop gradient:

And that's the result on my texture:

The real question is: what on earth did I create such a gradient for in the first place??

Mapping a texture to world coordinates. Part 2.

Example 1: blinking mask

Back on Enslaved, the environment artists used this method to map a gradient that would reveal some floor lights along a corridor so they would appear to blink sequentially.

This setup is very simple. This is the texture I'm using:

(It's actually vertical but I rotated it for the sake of this post's layout.)

Since there's a lot of black it will repeat less often.

And this is what the unreal material looks like. As you can see, it's nothing different from what I described in the previous post.

Now in the map, I've just put down a few small cubes with that material on and there I have my blinking lights (sort of).

and here's what the map looks like with the material on the ground plane.

It actually took me longer trying to optimize those gifs than it took to make the whole thing in unreal.

This is not the most exciting of all examples but more will come. Stay tuned.

Map a texture to world coordinates. Part 1.

Today we'll start looking at mapping a texture UVs to the world coordinates.
It's taking quite long to write the whole thing up so I'll keep the examples for later posts.

Mapping to world.

We've looked before at remapping a texture with another texture. The coordinates of a texture have vertical and horizontal data, which you can remap to whatever you want.
‘Whatever you want’ can be the world coordinates.
We're going to use the world position, but we need to divide it to start with. The values not quite usable as they are. The more you divide the world position, the larger the texture will be. It's sort of like zooming in your world: the texture appears larger.

The result is just like setting your texture tiling in a texture coordinates node.

Dividing the world by 500:

 

Dividing the world by 100:

Unlike your world, a texture has no depth, it only has two axis.
Next thing we need to know is the way your material will be oriented in the world so as to map the texture to the correct two axis. Imagine that you're facing a plane with your material on it. Which axis do you see pointing away ?
 
In our example we want to map it to the ground. If we look down from above, we see the R and G arrows pointing away. The z channel will not be visible.

 
So we use a component mask to keep only the R and G channel (x and y).


 Bear in mind that the texture will stretch along the third axis, the z axis in our case.

<teaser>
Would we be to use lerps and map the texture several times along different axis we could start to get a 3D feel. (at a cost obviously)
</teaser>

That's it for today, several examples will come soon.

Keep it local.

I'm preparing a future post which is growing by the minute. I'll probably have to break it down a bit to keep it clear. Here's a bit I'll refer to in the (near) future.

I mentioned the World Position minus Object World position to make things local before, but I didn't explain it properly. 

 The WorldPosition gives you the world position value per pixel, whereas the ObjectWorldPosition gives you the world position of your object, just the value at which its center is.

When you subtract the ObjectWorldPosition to the WorldPosition it means that every pixel will have a fixed value wherever you place it in the map. The value becomes relative to the center.

 

Imagine that this quad is in the world. We check the value of the same pixel at different arbitrary locations. WorldPosition - ObjectWorldPosition always returns the same value.

(Remember, if you're thinking of a formula don't just keep it abstract. Give it some numbers to verify that the result makes sense.)

This set up is useful if you want to be able to move your object around and you want the material to stick to it, it is also good for you to ‘tame’ your value.

Sometimes you can be testing a feature in your test map, but as you implement it in the game, some things will go crazy. Depending on where you are in a map, the output of the WorldPosition could range from 1 to tens of thousands. Would you be to use the WorldPosition as, say a multiplier, you can see where the troubles start.

We had that in DmC 5 with the summoner. She's a flying enemy so the character team put some vertex offset in her hair to give it a floating motion. To do so they used the world position to drive some sine waves. The first tests were looking good in the test map but her hair first went all over the place in gameplay. The fix was just a matter of subtracting the ObjectWorldPosition to the WorldPosition.