Posts Tagged ‘shaders’

[SPOILERS] Fun with shaders for LD37, part 3!

Posted by (twitter: @avaskoog)
Sunday, December 18th, 2016 5:03 pm

Hey! Posted part 1 and part 2 earlier about some of the custom shaders that were written for our LD37 entry, LOCK AND RELOAD. c:

Since the posts easily get a bit lengthy, I decided to divide this into a series of more bite-sized posts so that I don’t have to sacrifice all too much clarity for the sake of space. This is part three, about two shaders that make use of UV scrolling (sort of) and number two is a spoiler, so do play the game first! c;

(ノ◕ヮ◕)ノ*:・゚✧

Some of the effects are connected to slightly fundamental parts of the story, and since the game ended up being really short due to time constraints, I recommend you play the game first to avoid the spoilers and get the most out of the game with it’s little twists! So I’ll be adding a “read more” tag at to some parts to hide some of the stuff from the front page of the blog.

Note: the game was made in Unity and the shaders were written accordingly and so any code will be given as boiled down versions of the shader code written for that, but obviously everything is readily convertible to something like GLSL with minor to no changes.


 

Animated TV noise

In the small room that the game takes place there is a television set, and at the start of the game you’ll find that the screen is turned on, but showing nothing but static. Moving static, of course, and not just a frozen image!

View post on imgur.com

So how does this work? We could of course have gone super fancy and generate noise programmatically right there in the shader, but since we were not looking to do anything procedural here, that was completely unnecessary, and we’re only using a static texture with the noise already in it. The movement comes from randomly jumping around (rather than scrolling) the UV coördinates! ᕕ( ᐛ )ᕗ

UV scrolling

What does it mean to “scroll UV’s”, or “move UV coördinates around”? Well, the UV’s are what determine where and how textures will map onto a mesh/model. By moving the x and y positions of the UV’s along the surface onto which a texture is being rendered, the position of the texture will move. There are many neat uses for this, so let’s look at a few before we move on, just to make sure you understand! (◕‿◕✿)

View post on imgur.com

A waterfall is easy to achieve by scrolling a repeating texture vertically along a simple rectangular plane. In this particular case, there are multiple layers of textures moving at different speeds on top of each other, as well as some particle systems to help sell the effect further.

This next GIF was recorded from this YT video from the channel ClassicGameJunkie and their show How did they do that?, so go check that cool channel out! Its creator is also working on the 3D platformer Clive ‘N’ Wrench!

View post on imgur.com

The flat, cartoony eyes in The Legend of Zelda: Twilight Princess are best animated by scrolling the UV’s of the texture around the flat geometry rather than trying to actually move any vertices.

The noise texture

I admit! The briefing on UV scrolling was a filler, to some extent, because there isn’t very much to say about it. It’s very easy, at least now that you know how the concept works! c:

When UV’s scroll enough that we’re able to see one repetition of the texture meet another, there are two ways to go about rendering it. It can either be repeated/tiled, or it can be clamped. You may have seen these option before when looking at a texture in Unity’s inspector. To make it clearer what’s going on, let’s look at the noise texture in both modes:

ld37_shd_rep_clm

As you can see, clamping means that the last pixel of each side of the texture will be repeated indefinitely in the corresponding direction, while repeating means, well, repeating. This is what we want, since we want to be able to move to random locations on the texture and still get the TV screen filled up nicely with static.

The noise shader

Finally! As you would know, perhaps from the previous part, the basic way of going about shaders is to run the program on each pixel, or fragment, of something to be rendered, and process the final colour and alpha to output for each. To get the colour from the currently processed pixel, we just use the UV coördinate in the texture that we got from the previous part of the shader, the vertex part. Like so:

fixed4 col = tex2D(_MainTex, i.uv);

What we can do now is to add some numbers to the UV’s—an offset—that will move to a different part in the texture. We want this to happen in a way that looks random, and we want erratic jumping, not smoothly sliding over to the next part in the texture.

The thing to do when one does want to move smoothly around a texture would be to move by a constantly increasing value, like the game’s time. This might alternatively be plugged into some function, like cosine or sine, to move around in wavy or circular fashions.

We won’t do exactly that, of course, but we still need the time variable to have the conditions keep changing. What we can do to get the jagged movements we want is to make use of the modulo operator to see if the current time is divisible by some number, and use that as the basis of our stuff. We’ll even use some wave functions!

Since the rounded number will remain divisible by something until it has changed into something else that no longer is divisible by that number, we’ll be seeing each position where the UV’s end up for at least a few frames, which is of course what we want. We want this to change over time, so we’ll modulo the time by the time itself, but multiply each operand by a different number.

float factor = (time * 10) % (time * 22);

Something like that! That determines how much we move. Now to determine how far and where to move! We’ll use cosine and sine for this, again plugging in the time, multiplied perhaps by something else (or even nothing at all—i.e. 1.0—this time). This will make it move around in circles, but of course we won’t be able to see that as we only skip around on those circles.

float2 movement = float2(cos(time), sin(time) * distance;

The distance variable ensures that we move about a fair distance on the texture, so that the difference between each position is clear. And honestly, we might as well plug in something like time % 100 in there as well to make the noise as varied as possible!

And so we modify our initial line of code:

fixed4 col = tex2D(_MainTex, i.uv + movement * factor);

That’s it! Incredibly cheap cheating for some fake randomness that looks good enough for something like this, where the texture is already very random to begin with. I only used a texture that’s big enough to precisely cover the screen, but in retrospect I’d say this works even better with a texture that’s much bigger than the TV screen, to make any repetitions less obvious!

 


 

!!!ヽ(゚Д゚)ノ NEXT UP IS A SPOILER, SO THE “READ MORE” TAG WILL NOW BE INSERTED! ヽ(゚Д゚)ノ !!!

Thus you may want to play the game before you move on! c;

 


 

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[NO SPOILERS] Fun with shaders for LD37, part 2!

Posted by (twitter: @avaskoog)
Saturday, December 17th, 2016 9:45 am

Hey! Posted earlier about some of the custom shaders that were written for our LD37 entry, LOCK AND RELOAD. c:

Since the posts easily get a bit lengthy, I decided to divide this into a series of more bite-sized posts so that I don’t have to sacrifice all too much clarity for the sake of space. This is part two, about one of two shaders that make use of separate cameras and render textures!

(ノ◕ヮ◕)ノ*:・゚✧

Some of the effects are connected to slightly fundamental parts of the story, and since the game ended up being really short due to time constraints, I recommend you play the game first to avoid the spoilers and get the most out of the game with it’s little twists! So I’ll be adding a “read more” tag at to some parts to hide some of the stuff from the front page of the blog.

Note: the game was made in Unity and the shaders were written accordingly and so any code will be given as boiled down versions of the shader code written for that, but obviously everything is readily convertible to something like GLSL with minor to no changes.


 

Inventory inspection

This one is not a spoiler! c:

When picking something up, or clicking something on the inventory bar that was picked up earlier, the player will see a 3D view of the item in question along with some descriptive text.

View post on imgur.com

This view is rendered by a separate camera than the main one to get a nice 3D render of the spinning artefact. The main camera that renders the room (still visible behind the UI) cannot see this model, and the camera that renders the inventory view cannot see anything except the inventory item.

Separate camera setup

This is achieved in Unity by setting inventory items to a render layer of their own, and then unchecking that layer from the main camera, while unchecking everything except that layer on the inventory camera.

ld37_shd_insp_cams

Then you’re free to render your inventory and your game world in the same place, without them actually interfering with each other, like so:

ld37_shd_inv_scene_game

Render texture

Next, we need to create a texture for the inventory camera to render what it sees onto, since we don’t want it to render into the main game view and replace what the main camera sees. A render texture can be added by right-clicking somewhere in Unity’s file inspector and finding the option in the create menu.

It then needs to be connected to the camera, but we’ll not be using the field in the inspector for this, as it won’t work as intended. Instead we’ll be creating a small script that sets the camera up with the texture as the game starts. Something like this at the top:

[SerializeField] private Camera m_cam;
[SerializeField] private RenderTexture m_tex;

This way we’ll be able to drag and drop the camera and the render texture onto our script. Then as the game starts we’ll call this:

m_cam.targetTexture = m_tex;

Simple as that! Finally we’ll need to draw the texture somewhere so that we can see it. We’ll do this by adding a “raw image” to our UI canvas which will take the render texture as its sprite/texture, and that’s it. Now during runtime the UI will show what the inventory camera sees in that image, and we can edit the UI element as usual to get it to appear where we want it!

Remember we can also adjust the resolution of the render texture by opening it up in the inspector, in case the default 256×256 is too small, or has the wrong proportions.

The shader

You may have noticed we haven’t actually done any shader work yet! ヽ(゚Д゚)ノ

We can see there is a white border around the inventory item’s model, and also a circle behind it. But of course that’s not automatic. Without any shader, the inventory would now look like so:

ld37_shd_cabl_0

Not very fanciful, nor stylised. And potentially difficult to see, depending on the background! And of course this game’s UI has a dark overlay, so we want that white border around the model to make it stand out nicely no matter what’s below!

Border shaders can be tricky or not depending on the circumstances. In our case we’ve got a mostly transparent image with some non-transparent pixels in the middle; namely, those that make up the model. This makes it simple: we look for pixels that are transparent but have an adjacent non-transparent pixel at a particular distance from it (which will determine the thickness of the border), in which case we make those pixels as opaque as we wish and then assign the border colour to them! (◕‿◕✿)

Remember that we get the colour of the pixel/fragment at any given position in the texture by sampling a UV coördinate. To get the currently processed pixel, we just use the unmodified x and y that we got from the vertex shader:

fixed4 col = tex2D(_MainTex, i.uv);

To for the alpha value of any pixel around this one, we need to offset the UV coördinate by as much as it takes to move on to the next pixel. We’ll start simple, by only sampling the nearest pixels above, below, to the left and to the right of the current pixel. This gives us a less smooth border, but is easier to keep track of.

UV’s are normalised between 0.0 and 1.0, so to get the size of a pixel at this scale, we will need to divide 1.0 by the width and height of the texture’s resolution (in pixels). If we want our border to be thicker than one pixel, we can multiply the result by some value.

fixed2 one = fixed2(1.0 / width, 1.0 / height) * thickness;

Now we can get the alpha values around the current pixel by sampling the surrounding UV’s and only storing the alpha value and ignoring the RGB components.

fixed left = tex2D(_MainTex, i.uv - fixed2(one, 0.0)).a;
fixed right = tex2D(_MainTex, i.uv + fixed2(one, 0.0)).a;
fixed up = tex2D(_MainTex, i.uv - fixed2(0.0, one)).a;
fixed down = tex2D(_MainTex, i.uv + fixed2(0.0, one)).a;

The case may well be that up actually means positive values rather than negative depending on your coördinate system, but it makes absolutely no difference to the end result of this effect, so we need not worry about it. ᕕ( ᐛ )ᕗ

Now we can accumulate alpha values by adding all of these together, then clamping the result to 1.0 and do some more maths to finish up, which will be explained below the complete line of code.

fixed border = min(1.0, left + right + up + down) - col.a;
col.rgba += border * transparency;

Finally we subtract the alpha value of the original pixel that we are currently processing.

  • If all surrounding pixels as well as the original pixel are transparent, the end result will also be transparent, and we’ll either get no border at all, or a semi-transparent border pixel, which will give a nice and smooth result so long as the original model was also rendered with anti-aliasing.
  • If the original pixel was not transparent, the border value will be reduced (all the way to 0.0 if the original pixel was completely opaque; otherwise a semi-transparent value) and the original colour will overtake the border, since there will be nothing to add when we finally add the border value to all of the channels (RGBA) of the final colour.

We can also multiply the value we add by some factor below 1.0 to only apply a semi-transparent border. Et voilà!

ld37_shd_cabl_1

This border actually also samples pixels diagonally from the original pixel to make it even smoother. Note that this doubles the number of texture lookups, which can be slow, so choose carefully whether to add this extra overhead depending on the needs of your own application.

As you can see we still haven’t added that circle, but this post is getting lengthy, and you can get an idea of how to render a circle all in shader from the previous post. It’s one of the easiest things one can do, actually! Or you could just add a circle image to your UI below the UI image with the render texture if you’re not feeling up to it!

 

That’s it for this part! In the next one (and I won’t be posting it right away as I don’t want to be spammy), we’ll be talking about some UV scrolling shaders (one of which is a spoiler) before we move on to the second effect in the game that required extra cameras and render textures, which will be a SPOILER, so play the game first! c:

Remain at the edge of your seat! ☆

[NO SPOILERS] Fun with shaders for LD37, part 1!

Posted by (twitter: @avaskoog)
Friday, December 16th, 2016 2:34 pm

Hey! They’re not all too advanced, but I still thought I’d share a little something on the custom shaders that were written for our LD37 entry, LOCK AND RELOAD. c:

Since the posts easily get a bit lengthy, I’ll divide this into a series of more bite-sized posts so that I don’t have to sacrifice all too much clarity for the sake of space. We’ll start with the main shader that gives the game its look and feel!

(ノ◕ヮ◕)ノ*:・゚✧

Some of the effects are connected to slightly fundamental parts of the story, and since the game ended up being really short due to time constraints, I recommend you play the game first to avoid the spoilers and get the most out of the game with it’s little twists! So I’ll be adding a “read more” tag at to some parts to hide some of the stuff from the front page of the blog.

Note: the game was made in Unity and the shaders were written accordingly and so any code will be given as boiled down versions of the shader code written for that, but obviously everything is readily convertible to something like GLSL with minor to no changes.


 

Post effect filter

This one won’t spoil a thing as it is the very first thing to see upon starting the game: the wonky colour effects and checkerboard overlay. There’s also a dark vignette as well as some increased contrast.

View post on imgur.com

This effect applies to the whole final rendered image rather than individual objects and is therefore done in one step at the end of each frame, simply applying the shader to each pixel, or fragment.

Let’s go! ᕕ( ᐛ )ᕗ

The low-fi colour effect

This is achieved by first multiplying the colour values (which are all normalised between 0.0 and 1.0) by some factor, then rounding the numbers so that any resulting decimals disappear, and then dividing the values back down again by the original factor. This effectively decreases the colour variation. The smaller the factor, the greater the effect.

col.rgb *= factor;
col.rgb = round(col.rgb);
col.rgb /= factor;

ld37_shd_couleur

Contrast

The contrast effect is fundamentally not so complicated. It can be done in different ways, but for this particular game what I found worked best was to subtract some of the intensity of the colour if the original colour was below some tolerance value, but multiply it by some factor if it were above it.

col.rgb += (col.rgb < tolerance) ? 0.5 : 1.5;

ld37_shd_contr

Checkerboard

Alternating dark and bright squares are all over the screen. This isn’t some texture; just a little bit of maths. By checking the position of each pixel on the screen and figuring out whether it’s even using the modulo operator (which gives the remainder of a division), we can figure out whether the number is evenly divisible by two and thereby whether it’s odd or even.

If we multiply the coördinates by some factor to pretend that the screen is smaller or bigger than it really is, we can control how big the squares get. We apply the effect by darkening odd squares and leaving even ones untouched or vice versa.

col.rgb -= ((floor(x * s) % 2.0) - (floor(y * s) % 2.0)) * darkness;

ld37_shd_chekrs

Vignette

In this case, a vignette is a darkening of the corners of the screen. We’re basically applying darkness to the whole screen except an oval in the middle, leaving the corners dark but the middle unaffected. Circles are easy. We can achieve an oval by pretending that our rectangular canvas is in fact square.

fixed ratio = height / width;
fixed2 middle = fixed2(0.5 * ratio, 0.5);

We can then check the distance from the center to the current fragment, adjusted for the rectangle’s ratio, to get its position inside a circle, which will appear as an oval thanks to the ratio.

fixed2 pos = fixed2(x * ratio, y);
fixed factor = length(pos - middle);
col.rgb -= factor * darkness;

ld37_shd_vign1

You will probably want to adjust some values by multiplying them by various factors to make your vignette look the way you want.

That’s it for this part! In the next one (and I won’t be posting it right away as I don’t want to be spammy), we’ll be talking about the first of the two effects in the game that required extra cameras and render textures!

Stay tooned! ☆

Lighting Engine? Lighting Engine!

Monday, December 5th, 2016 5:43 pm

Hey everyone! We are in again.

So, we saw this post and this one. And I present you this:

LD37 warmup

illuminated js + phaser JS + VS Code

LD37 warmup

dynamic shadows in 2D?! Just look at the fence.

LD37 warmup

Mmm… Shaders

Actually it took a lot of work, couple of burned GPUs and 200+ lines of pure shader code.

I can’t wait to see you this weekend!

Assets source.

LD36 Update on A.R.C

Posted by (twitter: @@moongateuk)
Sunday, August 28th, 2016 5:17 am

Well I took  half a day off gamedev and ldjam yesterday for spend some time with a very good friend and my family, which has invigorated me to focus on this project in a much better mindset than I was in. So without further a-do, this is what A.R.C currently looks like.

I’m currently recording the whole development so I can put it up on youtube at somepoint in the near future.

ancient shader tech

Posted by (twitter: @heysnapshere)
Saturday, August 27th, 2016 6:18 am

I made this blue noise 3D->pixelart shader for my game.

actual game tomorrow cause its 4 am lol.

LD-Tech

Neko Katadzukeru: complete!

Posted by (twitter: @mahalis)
Sunday, April 17th, 2016 10:07 pm

Screen Shot 2016-04-17 at 6.15 p

I was polishing this until the very last minute—the cats were all white until about an hour before the deadline, when I started reworking all the assets so I could colorize them in a shader. The new assets look like this:

head@2x

With a couple of lines of GLSL, red areas get the “base” color, purple areas get the lighter version of that color, and green areas become pink. This way I could make arbitrary colors of cat without having to make a bunch of different versions of the same asset. I’ll go into more detail about that and some other fun tricks that went into this in a more detailed postmortem later on. For now, check out the game!

Xtreme Crop Duster Simulator ’82 – The Two-Camera Setup

Posted by (twitter: @rjhelms)
Monday, December 21st, 2015 11:58 am

After writing up my post-mortem for Xtreme Crop Duster Simulator ’82, I had a comment from pkenney asking about how the two-camera setup I created in Unity worked, and how I used Unity’s built-in shaders to achieve the graphical style of the game. A lot of the positive feedback I’ve received about the game makes reference to the graphical style, so I was already mulling the idea of a post about exactly that – the comment spurred me to actually write it up.

Lots of text and graphics to follow, which likely isn’t be applicable outside of Unity and may only be of interest to people keen on this sort of graphical style, so the real meat of the article follows the break. But as a teaser:

Before and after

Before and after

The challenge, which I had run into in previous Ludum Dares, is that square pixels are a relatively recent innovation. The Commodore 64’s multicolor low-resolution mode which I emulated in this game had a resolution of 160×200, displayed on a 4:3 television. This means that the pixels, once rendered, are 1.6 times as wide as they are tall – not a nice ratio to deal with. In my LD32 entry, Red Threat, I handwaved the problem away by drawing the sprites with 2:1 pixels, and scaling the whole thing up 2x to 640×400. It worked, but the effect was graphics that were noticeably stretched if you’re familiar with the real hardware.

This time around, I wanted to do better.

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Shaders, tentacles, and sinking!

Posted by (twitter: @mahalis)
Saturday, August 22nd, 2015 10:36 pm

Made the happy discovery that LÖVE supports pixel shaders now; used that to make the character’s tentacles more tentacley and to make a simple sinking effect for the boats.

tentacles and sinking

Step 14: HLSL. Writing pixel shader effect.

Posted by
Sunday, April 19th, 2009 12:04 pm

Construct doesn’t come with proper fade transition, so I thought about writing my own. Construct uses HLSL for effects, so I thought it’s a good chance to learn a bit about shader programming.

It was a failure (given the deadline pressure). I just gave up and decided not to use any transitions.

If by any chance anyone here is familiar with HLSL and knows or has an HLSL snippet which performs fade-away fade-in transition that would be great.

Do shaders count as “content”?

Posted by
Friday, April 17th, 2009 3:08 am

Just wondering:

Do HLSL shaders count as “content” (in which case they must be written during the compo) or “part of a graphics library” (in which case they can be written before the compo)?

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