Introduction
We finally started contacting Houdini. I have only heard of this software before, but I don’t know what its function is. But after I saw Tao’s work, such as the city with a bunch of buildings generated from a plane in Houdini, I thought it was really cool. What’s more, Luke said that Mehdi is proficient in Houdini, and I believe he will definitely help us understand this software better.
When I did the exercises, because I really didn’t know how to do it, I went to read a Houdini tutorial and learned about the operations that Mehdi didn’t talk about in the first lesson. I will also update some self-study projects. I hope I can, make progress in these exercises.
Tips：
- Note the location of the nodes.
- Press Enter to select items. Press 1234 to select Points, Edges, or Primitives.
- Houdini is very difficult. You have to be patient to learn.
Problems：
- Not fully understand the new concepts in Houdini such as SOP, VOP, DOP.
- I don’t really understand the difference between Vertex and Point
- Boolean one objects, but I can see its inside.
Process
When I watched the video, it actually lasted two hours, which means this is a very fulfilling course. So I watched it while taking notes.
There are a lot of new concepts in this, and I think the new concepts in Houdini are unfamiliar.
Thank you Tina for sharing her notes, which I think are more detailed than the instructions I found on the Internet:
SOPs = Surface OPerators or geometry nodes that are inside an object folder. These are used to construct and modify geometry. Any kind of geometry from polygons to volumes.
DOPs = Dynamic OPerators or simulation/solver nodes that are used to construct simulations. Simulations read in geometry from SOPs and passes this data in to the DOP solvers.
SHOP = SHading Operators are materials that represent a shader to apply to geometry. Some are hard coded with vex and others are folders that you can dive in to and modify the VOPs inside.
VOPs = Vector OPerators inside VOP network nodes are used for everything from building shaders to modifying geometry, volumes, pixels, and more.
VEX = Vector Expression Language. The code language used to write shaders. VOPs are wrappers around VEX code snippets.
COPs = Composite OPerators in composite type folders. Used in image compositing operations.
ROPs = Render OPerators in side ROP Output directories which are used to create render output dependency graphs for automating output of any type of data and for triggering external processes like rendering. Commonly used to generate sequences of geometry, simulation data and trigger Render tasks that generates sequences of images to disk.
At that time, I still didn’t know these concepts well, and I didn’t know how to use them (or this is just a concept), I hope Mehdi can explain them one by one later.
Exercise01 – Rock
Because using the sphere to make the stone is not as good as the cube in the shape, we first use cube and subdivide to smooth the edges to make a model similar to a circle.
The teacher encourages us to try different options more, which may have different effects, so even though I may not know what effect this will cause, I also tried to adjust some buttons.
【210216 update】Now I understand a very important piece of knowledge, why in attribnoise, the model only changes when Attribute Names and Attribute Class are Vector-P and Points. Because Position is Vector, and Point is also represented by vector. Vertex is not a vector, so the model will not be changed.
In the beginning, no matter how I modify the values, my model is still very rough. After watching the teacher’s video again, I found that my subdivisions were not enough, so I increased the subdivisions again. But also because of this my Houdini stuck.
As long as you have patience, you can make a stone, although I don’t think I made a stone.
Exercise02 – Wooden Cabin
I plan to try to make it with only one box as the basic model. I hope that no matter how scaled my model is, it will always be above ground level. So what I need to change is the value of Size Y and Center Y. Of course, when Size Y is changed, Center Y will also change, so that the model can move while zooming, and it will stay above the ground plane.
Using this principle, I succeeded in making the door change with the change of the house. So if I want to modify the model, all the models will follow the changes, which is very convenient!
Then I built the windows, but this time I did not use expressions, so the windows will not change with the house. twenty two
When I watched the video, I was not very clear about the principle of delete, so I went to help to view the explanation of this node.
At the same time, because I know there is a node called blast, the principle is similar to delete, so I did not use two deletes following the operation of the teacher (but this is more convenient). After I know the number on the bottom, I can enter a number in the group to delete this primitive.
But I ran into a big problem. My house is not flat roofed like the teacher’s. My roof is triangular. And I don’t know how to modify the edges. I thought of many ways, such as inserting edge loops like Maya, but I am not very familiar with this software, so I don’t know how to operate. Finally, I finally know that by selecting Polygon Mesh in Primitive Type, you can see Mesh. However, although I can see the edges, I cannot select them, even if I press Geometry select mode on the left side of the screen. So I had to search the Internet for answers. Finally found a solution: press Enter to enter the object selection mode, and then use 1234 to change the selected object.
The result finally showed a strange model. After I checked, I found that I put the node of the modified edge on the top, which also affected the model of doors and windows. This shows how important the position of the node is.
Now I need to make the roof and floor that have just been deleted and blasted. I duplicated the delete and blast nodes, and then selected Delete Non Selected. This is a bit similar to the inverse selection of Photoshop, so you can use the same node to modify, which can save time. Separating the roof and the floor, I used polyextrude and transform to generate thickness and scale for them, and finally displayed all of them with merge, and my house was almost complete!
I want to use copy and transform to replicate the feeling of multiple boards and then paste them on the wooden house. Among them, the wooden board group on the front also had to be Boolean with the doors and windows, but after making it, there was a wall blocking the front. I don’t know what it came from, so I had to check the node graph again.
I moved the position of polyextrude2, but the place where the Boolean cut is empty, and the inside of the model can be seen from the side, which is wrong.
But I successfully solved it! ! ! I really studied for a long time and tried many combinations of nodes. In the end I recreated two booleans, just connecting the board groups. Then I changed the original surface (so the original wall was to be Extruded) to Solid, so that the board group would not be cut into surfaces, but solid. Although there are more nodes, this is a way I can think of! 353637
This is my final output and node graph! I am really happy I made this! 3839
Conclusion
I have to say that Houdini is really difficult to use. I really checked a lot of information before I made a small house. But when I can use expressions and add and delete nodes in Houdini, it means I have a new idea of making objects. I hope I can continue to learn this interesting software.