Changsoo Eun

Welcome to my 3rd OSL tutorial! In this tutorial, we well learn how to query scene/object data and utilize it with MATH! Yes, you heard it right. MATH! I know you always have been regretted that you didn’t pay attention to the math class when you were in middle school. But, never late than never. Re-learning some simple math will make your life easier. WE CAN DO IT TOGETHER!

Like always, we will not write a single line of code in this tutorial. We will use SlateME as our OSL editor. Let me say it again, YOU DON’T NEED TO KNOW HOW TO CODE TO USE OSL IN 3dsMax.

I’ll use MeetMat2 for this tutorial. You can download from Substance website.

First, let’s see how we can query the position of pixel in the scene and utilize. For example, we can make a transition of 2 maps between certain heights from the ground.

You can use “Named Coord Space” map to get a position of a coordinate space.Let’s make one and s some basic setup for the tutorial.

• Make “Named Coord Space” map and a Standard material.
• Make Self-Illumination 100.
• Connect UVW of “Named Coord Space” to the Diffuse Color of Standard material.
• Make sure to turn on Show Realistic Material in Viewport.
• Select “High Quality” mode in the viewport.
• Apply the Standard material to Mat.

3dsMax OSL has an amazing OSL > HLSL auto conversion features as I posted before. You can see OSL map exactly same as render in viewport for most cases. All OSL map has a indicator at the bottom to show if this map could be displayed in viewport. To utilize this feature, your material must set to Show Realistic Material in Viewport, and your viewport must set to Advanced Rendering mode which High Quality preset has.

Your viewport should like this if you follow me correctly. What you are seeing is the World coordinate position as color. If you know what is World coordinate and Object coordinate, you can jump to the next section.

World position is the position from the world origin. Since we plug X, Y, Z, into R, G, B. You can see more Red color along X. Green along Y, Blue along Z. Color can only display from 0-1, that’s why you can only see a little gradient around an axis. Mat’s size is 8.2×1.0x9.4. If value is less than 0, it will be all black. If you rotate the model, you can see the color is not moving with object. Because the coordinate is fixed in world.

Another coordinate you might use is “Object” which is based on each object’s local coordinate. The origin will be at object’s pivot point. The axis will use object’s local axis. This means when the object is moving or rotating, the value will move with objects. If you need to make a map that is stick to the object, this is coordinate you need to use.

Now you know what World/Object position is and how to get the value with “Named Coord Space” map. Let’s utilize the value we got. We will try to blend 2 check map along the height(Z-axis)

• Make a Maps > OSL > Math Vector > Component (Vector ).
• Connect UVW of Named Coord Space to Input of Component (Vector)
• Make a Maps > OSL > Math Float> Range/Remapper.
• Connect Z of Named Coord Space to Input Value of Range/Remapper
• Connect Out of Range/Remapper to Diffuse Color of the Standard material.
  

This should be what it looks like. BTW, I turned off AO. What’s happening here. We took only Z axis value with Component (Vector) map. This map is you can separate each channel from a vector or assemble a vector from 3 floats. Then, we fed the Z value to Range/Remapper which doesn’t do anything with default values. You can see the gradient goes from 0 to height 1. Again, as a color we can only visualize 0-1. I put 1 unit height box as reference.

Now we need to manipulate this value so the value can go from 0.0 – 1.0 between height 1.5 – 3.5. That’s what Range/Remapper  does. Click the map and set Input Range Start to 1.5, Input Range End to 3.5. Now this map takes World Z position as Input Value. You can see “M” button shows that the value is coming from the connection, Then, map the input value 1.5 – 3.5 as 0.0 – 1.0 as output.  You can visually see the gradient is moved up and 2x wider.

We can utilize this value as the Mix value for Mix map.Mix map is a map that Mix 2 color. Surprise! I could use Composite Map, too. But, this map is simpler. Also this is a tutorial. You gotta something new.

• Make a Maps > OSL > Math Color > Mix(Color) map.
• Make 2 OSL checker map with different colors and Size 0.05.
• Connect each Checker map as A and B of Mix(Color) map.
• Connect Out of Range/Remapper to Mix of Mix(Color) map.

Now let’s make it a little bit more complicated. What if I want to have blue check only top of Mat’s head like snow on his head. We can utilize normal for that.

You can get the normal data with Normal map. Duh. It is under Scene Attribute. It has one option, Coordspace. It should be “World”. Normal is “normal is an object such as a line, ray, or vector that is perpendicular to a given object.” according to Wiki. You can thin think as an arrow that coming out of a face. OK, that’s cool. But, so what? How can it help me?

Usually you need two sidekicks to utilize the Normal data, “Dot product” and another vector. Wha… WTH is “Dot poduct”? My head is already hurting!!! If you really want to know what it is. You can suffer from reading this. Butm I have a good news for ya. You don’t actually need to know what it is. We just need to know how to use this.

• Make a Maps > OSL > Math Vector > Dot product (vector).
• Make a Maps > OSL > Values > Vector Value.
  Put 1.0 as Z value. Make sure X, Y are 0.0
• Make a Maps > OSL > Scene Attribute > Normal.
• Connect Out of Normal to A of Dot product (vector).
• Connect Out of Vector Value to B of Dot product (vector).
• Connect Out of  Dot product (vector) to the Diffuse Color of Standard material.
  

What did we just do? It looks like face becomes whiter if it face more to the top. When you dot product 3 vectors, Normal and [0, 0, 1] for us. The more 2 vectors look the same direction, The result becomes closer to 1.0. If two vectors are aligned exactly and toward same( direction. the dot product becomes 1.0. If two vectors are at right angle(90 degree), the dot product becomes 0.0. If two vectors are looking at the exact opposite direction. the dot product becomes -1.0. That’s all you need to know. This is how Falloff map works under the hood.

just for the test’s sake, change the vector Z value to -1.0. As you expected, it gets whiter as the point more face down.

How about X = 1.0 and Y, X =0.0?

Got it? Then, Let’s set back to [0, 0, 1].

Now we need some house cleaning. When you dealing with normals and dot product. It is always a good idea to normalize the incoming vectors like this. this makes the incoming vector as a unit vector. If you don’t want to know what/why. just memorize and do it. It is good for you. Normal map is at Maps > OSL > Math Vector > Normalize (vector).

Another item for house cleaning is Clamp. As I mentioned above, dot product generates value from -1.0 to 1.0. You can not see the negative value in render or viewport since both only shows between 0.0 – 1.0. But, if you use negative value for other operation, it could cause issues, therefore. it is always a good idea to cut negative values with Clamp map. Clamp map limits any value outside of Min and Max value as Min and Max value. The default is 0.0 and 1.0. So, any value less than 0.0 will become 0.0. Any value bigger than 1.0 will become 1.0. The map is in Maps > OSL > Math Float > Clamp.

OK. Now we have 2 map trees. One for blending by height. Another one for the direction. We want to combine both so we can have blue check only at the top of Mat’s head. For this kinds of case, we can simply multiply two masks.

• Select Range/Remapper. Set Input Range Start to 3.0, Input Range End to 4.0.
  This should move mas above Mat’s head.
• Make a Maps > OSL > Math Float > Multiply map
• Connect Out of Range/Remapper to A of Multiply.
• Connect Out of Clamp to B of Multiply.

I know… after all those node, what you got is not that cool. But, this is how you learn.

In this tutorial…

• we learned how to get position and normal information from the scene
• how to utilize normal with dot product
• many of frequently used important math maps such as Range/Remapper, Clamp, Normalize, Multiply. Component.

BUT! Yes, there is always BUT!

The portion that we used to make a mask by face normal exist as one map, Falloff map. This map is basically same as the map tree we set up with a bunch of maps. It take cares Normalize and Clamp, it also have option to map ti the different range. It also allow to define each end as color which is same as Remapping the result with Gradient.

In Falloff map, you have coordinate to choose just like Normal map. You have Face and Away color for each end. Face means the color when dot product is 1.o. Away is the color when dot product is 0 because Type is Perpendicular/Parallel. If you switch to Toward/Away. The Color will map between dot product 1.0 to -1.0.

Thanks!

Do you like my OSL mini tutorial series? Then click here and check out renderStacks, too!

Welcome to my second OSL tutorial. Again, we will not write a single line of code in this tutorial. We will use SlateME as our OSL editor. Let me say it again, YOU DON’T NEED TO KNOW HOW TO CODE TO USE OSL IN 3dsMax.

I don’t want to spoil the ending. But, you should read til the end. 🙂

One of the advantage(or could be disadvantage for some users) of using OSL in 3dsMax is that it brings more granular and lower level of control which provide a greater flexibility. But, it also means that user need to learn and understand a new way of thinking(or workflow). Again it doesn’t mean you need to learn to code. But, you need to understand how and what kinds of data is flowing between lower level maps and how to control them. So, please try pay more attention to the explanation of “why” I’m connect port A to port B instead of memorizing map tree. 🙂

Today’s goal is randomizing textures in the tiles of Simple Tiles OSL shader so we can get infinite random tile texture from a few texture files.

1. 1. Open SlateME.
   2. Make a Simple Tiles map. Maps > OSL > Textures > Simple Tiles.
      This is an equivalent of Tiles legacy map. You can make a various tile or brick patterns.
   3. Double click the thumbnail so we can have a bugger thumbnail.
   4. Change Tiling Mode to Twist Box.

As you can see, OSL can output not only color information but also various data information. For this tutorial, we will mainly utilize Index data which is a integer index number for individual tiles. Let’s see that it means visually.

1. 1. Make 2 OSL > Math Float > Random by Index.
   2. Connect Index port of Simple Tiles to Idx of both Random by Index map.

So, what’s happening here?

Random by Index map generates a random float number between Min and Max and drives the randomization with the Idx and Seed parameters.

Since Idx of Random by Index is provided by the Index value of Simple Tiles, all pixels in the same tile will get the same random value.You can see that well from the thumbnail, each tile has a different shade of gray.

But, you can see both map has exactly same pattern and color. That’s because both map has same Seed number by default. What is the Seed number? This is from the Wikipedia. “A random seed (or seed state, or just seed) is a number (or vector) used to initialize a pseudorandom number generator.”, which brings another important concept, pseudorandom.

In CG, we can not use true random number, if a number is truly random. That means every time when you render or even open file again. You will have a different number and different pattern! Therefore, all random number in CG is pseudorandom driven by Seed number. If Seed number is same you get the same ransom number just like the above image.

1. Select the bottom Random by Index map
2. Set Seed to “77”, You should get this.
   

OK. let’s make a bunch more maps and actually do something with these 2 random maps.

1. Make the following maps
   OSL > Math Vector > Component (Vector)
   OSL > UVWCoordinates > UVW Transform
   OSL > BitmapLookUp
2. Choose “C:\Program Files\Autodesk\3ds Max 2021\maps\uvwunwrap\uv_checker.png” for BitmapLookUp
   This is a new 4k UV template which is added in 2021.
3. Connect Out of the top Random by Index > X of Component (Vector)
4. Connect Out of the bottom Random by Index > Y of Component (Vector)
   
5. Connect Out of the Component (Vector) > Offset of UVW Transform
   Do not connect anything to BitmapLookUp yet.
   
   

The 2 Random by Index we made were for the random Offset value of UVW, and it is a vector value. How do I know? If you see in UI, you can ses that it is made out of 3 values. The, it is a vector value.

So, we can not directly plug 2 float values into the Offset port. We need to assemble a vector data and plug into Offset. Component (Vector) map allow to compose or decompose a vector from/to 3 floats. Since we need to use only X and Y value. you don’t have to plug anything into Z. If no map is connected to the property, OSL map will use the value in the UI which was 0.

What we got so far? As you see in the thumbnail of UVW Transform, we randomly offset UV per tile. If you see more red, that means the pixel is offset more along U. If you see more green, that means the pixel is offset more along V. Remember Slate can only show any value range from 0-1 because it is made for color. Fortunately this case out data range is also 0-1. So, we could see what’s going on as image. But, it would be be the case all the time.

1. Now Connect UVW of the UVW Transform > UV Coordinates of BitmapLookUp
   Tada! you can see your texture randomly offset by Tile ID.
   
   

Cool. Now how can I control the scale of texture? Yes, you change the Scale value of UVW Transform.

How can I control the size of tiles? Scale in Simple Tiles.

Let’s see what it looks like with a real texture. Remember this technique only works with seamless tileable texture. This is with the TexturesCom_RockSmooth0172_1_seamless_S.jpg from here. https://www.textures.com/. I use scale to 5.0 for UV.

How about some mid tone variation? We can use Tweak/Levels OSL map for this. We will also need another Random by Index map driven by Index.

1. Select one of Random by Index map and SHIFT+drag to make a copy.
2. Set Min as 0.75, Max as 1.25. Seed as 131.
3. Add a OSL > Tweak/Levels map.
4. Connect Out of the new Random by Index map to MidTones of Tweak/Levels.
5. Connect Out(RGB) of BitmapLookUp map to the Input of Tweak/Levels.
   

OK, I hope you get the hang of how to wrangle data to drive values at this point. Next, let’s put the gaps in. There are unlimited ways to how to handle gaps. But, I’ll just go easiest way since the main purpose of this post is tutorial. The Bump output of Simple Tiles map already give you a black gaps and white tiles. I’ll use that output to composite with Multiply mode.

1. Make OSL > Compositing > Composite map.
2. Connect Out of the Tweak/Levels > Bottom layer RGB of Composite
3. Connect Bump of the Simple Tiles  > Top layer RGB of Composite
4. Set Top layer Alpha as 0.7, BlendMode as Multiply.
   

OK, it is getting there. Let’s add one more randomization, the rotation. By now, you should already know what to do.Yes, you need to have another Random by Index (Float) with range 0.1 – 360 and feed into Rotate of UVW Transform. BUT, since it is a tutorial, let’s make things more complicate to learn. What if we want to rotate only at right angle like 90, 180, 270 degree?

Our goal is get only one of the 0, 90, 180. 270 per tile. How we do that? Right, we can get a random value between 0 – 3 and multiply 90.0. But, Random by Index (Float) generates float number, and we don’t have Random by Index (Integer) map. Well, don’t worry. Here comes Float-to-Int map to the rescue!

1. Copy one of Random by Index (Float).
2. Set Min as 0.0, Max as 3.99. Seed as 666.
3. Make OSL > Math Float > Float-to-Int map
4. Set Mode as floor.
5. Make OSL > Math Float > Multiply map
6. Set B as 90.0
7. Connect Out of the new Random by Index map to Input of Float-to-Int.
8. Connect Out of the Float-to-Int map to A of Multiply
9. Connect Out of the Multiply map to Rotate of UVW Transform.
   You may wonder why 3.99 instead of 3.00, and what the heck is “floor”? Floor is a way to convert a float value to integer value by returning the largest whole number (integer) that is less than or equal to the number. if you had 1.24, you would get 1.o. So, it is a floor of the range 1.0-2.0. There is also “ceil” which is kinda opposite. The ceil of 1.24 would be 2.0. By setting range as 0.0-3.99 and mode as floor, we are trying to make sure all 4 numbers are getting even chance. 0.0-1;0 > 0.0. 1.0-1.99 > 1, 2.0-2.99 > 2.0. 3.0-3.99 > 3.0.
   Left is without the rotation randomization. Right is with the rotation randomization.
   

As you can see, you can randomize any parameters you want. You just need to know when to stop. Should we stop now then? No, not yet. So far, we have used only one map file and looks like getting a good result. But, what if we can use multiple map files and randomly use per file?

Here is a great news. One of the new feature of 3dsMax 2021.2 is 1-of-N(Filename) map. If we don’t have this map, we have to setup a small tree with multiple BitmapLookup , 1-of-N Switcher and Random by Index map. Now we just need 2 maps.

1. Add a OSL > Switchers > 1-of-N(Filename) map.
2. Choose all 5 maps.
3. Add a OSL > Switchers > Random Index by Number/Color map. BTW, such a great map, I wonder who made this? 🙂
4. Connect Index of the Simple Tiles map to Input Number of Random Index by Number/Color.
5. Connect Out of the Random Index by Number/Color to Filename of BitmapLookUp.
   

OK… This is the full tree. I guess we end up with not-so-mini-tutorial.

BUT! Yes, there is always. “BUT”.

We went through all these to learn how to work with OSL maps to build own randomization. Now I have to tell you this. Sorry, we didn’t need to go through all these if you wanted to just use it. Why? Because Zap made the awesome Bitmap Random Tiling for 3dsMax 2021.2.

This is what it looks like if you use Bitmap Random Tiling. Youjust need to plug Index into Seed. Make sure to turn off Randomize by UV position.

You can even randomize color, too.

If you want to use multiple map file? Then, re-use the 1-of-N(Filename). Another 2021.2 feature.

I guess it is worth to upgrade??? 🙂

If you are really lazy, here is the max file. It has the full setup and simple 2021.2 setup. I can not include texture file. So, you probably need to download some seamless tileable maps. Here is another good news. Because ,max file actually embed the source OSL code in the scene file, you can even open this file in 2019. You will see the new 2021.2 OSL shader there. Save the OSL map in a material library. Then, you can even use the new map in 2019 or 2020.  Another nice thing about 3dsMax OSL implementation!

Since you follow me all the way down here, you need to check renderStacks. Click here!

A teaser for the future article! What is the difference between the following 4 images?

The answer is… they all rendered in a different renderer. From the left, Corona, VRay, VRayGPU, Arnold. Yes, all different renderer. You can have exactly same map tree across different renderer even CPU/GPU. I can say this is the first time I ever see this is possible in CG history. I’ll have a blog post with more examples in the future.