Unwrapping simple shapes quickly can help you efficiently texture background objects in a scene. The UV Texture node allows you to do just that. Take a look at its controls and how you can get the best viewport feedback out of it.
- [Instructor] As with many DCC applications, Houdini has several approaches or tools that can be used when it comes time to create UV mapping in our project. In certain situations, choosing one over another can not only speed up how it'd work, but possibly give us better results as well. In this exercise then, we're going to look at the UV texture node and see why we may prefer to make use of this particular tool in certain situations. In our seam view then, let's double click to enter the pillar's geometry graph and press the tab key so that we can search for and add a UV texture node.
As we will sometimes want Houdini to do a measure of any grunt work for us, in this case applying our UV maps in an automated way, let's place our UV texture node above the copy and transform node so that as the copies are made, the UV mapping that has been applied automatically goes along for the ride. Taking the time to figure out where the best point in the flow is to place our map and nodes can be an important part of the process, so try not to rush through it. Next, let's take a look at the texture type drop down, which by default is set to author graphic, meaning it is taking a single plane and projecting the texture onto the geometry along a specific axis, in this case Y.
Now we could say from the top down, seeing as the view port makes it clear that Y is the up axis for the object. This makes the mapping approach perfect for flat objects such as manmade floors, or with the flip of the projection axes, flat walls. Let's try the next choice then, which is polar. Now, whilst this is better for this particular mesh, it still isn't perfect, because polar uses a sphere to project a texture onto the geometry. As a sphere curves away from the flat faces of the cylinder, however, the mapping distorts and so looks wrong.
As you have probably guessed, the next choice available is actually the one that we want, which is cylindrical. Again, because our axes is set to Y, the projection cylinder is oriented correctly, and so we get a mapping result that suits the object's shape. Although, if we use the alt key and middle mouse combo to swing around and view the side of our cylinder, we can see that things have still gone wrong. Now this is because the start and end points of our texture are actually using the same vertices to store UV data.
Because this is, well, impossible, we get a visual error as the entire map gets squashed into the seam faces. To fix this, the application essentially needs to make a duplicate of the UV edges and vertices, and then assign either the start or the end of our map to them. To do this, we can click the fix boundary seams checkbox, then we are good to go. This is especially important to know, should we be creating UV mapping on geometry that needs to go into a game engine.
Given the facts that this problem will exist for all seams in the UV map, and so the more seams we have, the more vertices and edges need to be duplicated in order to make the seams map correctly. The more of these we have in our final model, the more we can adversely impact the game's performance. The UV texture node then can be a great solution for quickly adding mapping to meshes that conform to somewhat simple shapes in their general outline, so objects such as floors and walls, pillars and pipes and wires, and of course for our spherical objects as well.
Not that this is all that the UV texture node is good for, as it has even more to offer when it comes to quick and efficient mapping setup, as we will see in our next video.
- UV mapping basics
- Controlling how UV mapping handles scale
- Displaying viewport maps correctly
- Testing and resetting UVs
- Choosing a texture type
- Mapping NURBS and Bézier surfaces
- Making UV seams
- Grouping, storing, and reusing UV seam selections
- Using seams with pelt mapping
- Selecting and manipulating UVs
- Sewing shared points
- Installing the Game Development Toolset