I'm wondering when should I use different UV Set options in the Unity Standard shader.
I know that UV stands for the texture coordinates, but what would I need to switch to uv1 instead of uv0? I cannot see any immediate difference when I switch between them and Unity docs doesn't seem to explain much.
Perhaps somebody could shed some light on when different sets need to be used.
Just for the sake of completeness: UV coordinates are assigned in model creation tools (Maya, Max, Blender etc.) not in Unity. So Unity just gives you access to a limited number of UV maps you may or may not have exported from afore-mentioned tools. That's why there isn't more documentation on UV sets, because they are an optional additional feature of an imported model.
There are scenarios in which more than one UV map is necessary or more elegant/performant. You can have shaders that use different UV coordinates for different maps. One example would be a shader that adds a detail map to a model which requires a different set of UV coordinates (independent from the base UV map which is used for the other maps like albedo, normals etc.)
You are not limited to switching between uv0 and uv1. You can use them in combination as well, if you create a shader that makes use of both maps. I think this is even more common than switching between different UV maps.
Related
I have a point-cloud and a rgb texture that fit together from a depth camera. I procedurally created a mesh from a selected part of the point-cloud implementing the quickhull 3D algorithm for mesh creation.
Now, somehow I need to apply the texture that I have to that mesh. Note that there can be multiple selected parts of the point-cloud thus making multiple objects that need the texture. The texture is just a basic 720p file that should be applied to the mesh material.
Basically I have to do this: https://www.andreasjakl.com/capturing-3d-point-cloud-intel-realsense-converting-mesh-meshlab/ but inside Unity. (I'm also using a RealSense camera)
I tried with a decal shader but the result is not precise. The UV map is completely twisted from the creation process, and I'm not sure how to generate a correct one.
UV and the mesh
I only have two ideas but don't really know if they'll work/how to do them.
Try to create a correct UV and then wrap the texture around somehow
Somehow bake colors to vertices and then use vertex colors to create the desired effect.
What other things could I try?
I'm working on quite a similar problem. But in my case I just want to create a complete mesh from the point cloud. Not just a quickhull, because I don't want to lose any depth information.
I'm nearly done with the mesh algorithm (just need to do some optimizations). Quite challenging now is to match the RGB camera's texture with the depth camera sensor's point cloud, because they of course have a different viewport.
Intel RealSense provides an interesting whitepaper about this problem and as far as I know the SDK corrects these different perspectives with uv mapping and provides a red/green uv map stream for your shader.
Maybe the short report can help you out. Here's the link. I'm also very interested in what you are doing. Please keep us up to date.
Regards
There are some ideas I would like to do in shader that require me to make a weird texture topology, texture atlas packing for example. They could not be wrapped with common wrap mode, there would be glitch or bleeding on the edge of UV seam
And so I think, what if I just use tex2D() or tex2Dlod() for texture lookup with point filtering, and then rewrite all sampling and blending logic in the shader itself, look up for many points with custom wrapper and blend them with shader code
Is it possible and what could be a problem or disadvantage about this method?
Yes, this is possible and common. You will need to set the filter and/or wrap mode of the texture asset itself, in the project. (if using shader graph, you have the option to specify a custom sample state inside the shader itself). You can certainly modify the UV coordinates passed to your shader, and use those modified values to sample the texture(s).
Perhaps the question is not that correct, the textures should be say a kind of channel? although I know they will be mixed in the shader finally.
I know the knowledge of the various textures is very important, but also a bit hard to understand completely.
From my understanding:
diffuse - the 'real' color of an object without light involved.
light - for static objects. render light effections into texture beforehand.
specular - the area where has direct reflection.
ao - to absorb indirect light for the different area of an object.
alpha - to 'shape' the object.
emissive - self illuminance.
normal - pixel normal vector to deal with the light ray.
bump - (dont' know the exact differences between normalmap).
height - stores Z range values, to generate terrain, modify vertex etc.
And the items below should be related to PBR material which I'm not familiar with:
translucency / cavity / metalness / roughness etc...
Please correct me if some misunderstandings there.
But whatever, my question is why we need to separate these textures apart for a material but not only render them together into the diffusemap directly for a static object?
It'll be appreciated if some examples (especially for PBR) , and thank you very much.
I can beforehand bake all things into the diffuse map and apply to my
mesh, why I need to apply so many different textures?
Re-usability:
Most games re-use textures to reduce the size of the game. You can't if you combine them together. For example, when you two similar objects but you want to randomize the looks of them(aging effect), you can make them share the-same color(albedo) map but use different ao map. This becomes important when there hundreds of objects, you can use different combination of texture maps on similar objects to create unique Objects. If you have combined this into one, it would be impossible to share it with other similar objects but you to slightly make to look different.
Customize-able:
If you separate them, you'll be able to change the amount of effect each texture will apply to the Object. For example, the slider on the metallic slot for the Standard shader. There are more of this sliders on other map slots but they only appear once you plug a texture into the slot. You can't do this when you combine the textures into one.
Shader:
The standard shader can't do this so you have to learn how to write shader since you can't use one image to get the effects you would with all those texture maps with the standard shader. A custom shader is required and you need a way to read the information about the maps in the combined shader.
This seems like a reasonable place to start:
https://en.wikipedia.org/wiki/Texture_mapping
A texture map is an image applied (mapped) to the surface of a shape or polygon. This may be a bitmap image or a procedural texture. They may be stored in common image file formats, referenced by 3d model formats or material definitions, and assembled into resource bundles.
I would add to this that the shape or a polygon don't have to belong to 3d objects as one may imagine it. If you render two triangles as a rectangle, you can run all sorts of computations and store it in a "live" texture.
Texture mapping is a method for defining high frequency detail, surface texture, or color information on a computer-generated graphic or 3D model. Its application to 3D graphics was pioneered by Edwin Catmull in 1974.
What this detail represents is either some agreed upon format to represent some property, (say "roughness" within some BRDF model) which you would encounter if you are using some kind of an engine.
Or whatever you decide that detail to be, if you are writing your own engine. You can decide to store whatever you want, however you want it.
You'll notice on the link that different "mapping" techniques are mentioned, each with their own page. This is the result of some person, or people who did some research and came up with a paper detailing the technique. Other people adopt it, and that's how they find their way into engines.
There is no rule saying these can't be combined.
I've built a working surface shader (call it "wonderland") that renders as invisible unless a companion "lookingGlass" shader intersects with it from the viewpoint of the camera. Simple stencil shader arrangement.
Easy peasy.
I can add shader settings to specify a plane, or even just a minimum worldspace Z value, and use clip() to only render pixels on one side of that plane... (in other words, I could use that to trim the content that's allowed by the Stencil.)
What I want to do is use the stencil on surfaces "through the looking glass", (to reveal geometry that's inside the looking glass) and to always render those surfaces when they're on "our" side of the looking glass (to always show them if they're on this side of the looking glass portal). eg., if z<0, render if the Stencil Ref value is satisfied. if z>=0, render regardless.
Now, in Unity I can attach two materials to the MeshRenderer component (one with a stencil shader, one with a "plane cutoff" shader) - that works fine. It's pretty awesome, actually, at least visually. But while I haven't benchmarked it yet, I instinctively believe it's going to massively impact framerate if there are a number of objects, fairly complicated geometry, etc., set up with this arrangement.
(I can also manage shader attachment in code, and only do this when I expect something to transition, but I'm really hoping to get a unified shader out of this to avoid unnecessary draw calls.)
As it turns out, what I was looking to do is impossible.
The two shaders I wish to combine are both surface shaders. While you can combine multiple surface shaders into a multipass shader, you cannot combine multiple surface shaders, with a Stencil, and with a clip() where the clip is applied to passes that the Stencil is not and vice-versa.
There are combinations that can achieve parts of this, or can achieve the entire goal with surface and vert (or other non-surf) shaders, but the combination of requirements stipulated by this question isn't supported as desired.
While this does not answer the question, the workaround in Unity is to create two materials that provide each piece of functionality. They can both exist on the item that needs both pieces, and code can otherwise manage whether one or the other or both is actively in use.
Similar solutions would be available in other packages.
I want glow on my sprites using the UV coordinates, but the problem is, if the sprite originates from an atlas created by Unity's sprite packer, then the UV aren't normalized from 0 to 1, but from and to two arbitrary values. How do I normalize UV data for a single sprite that resides in an atlas? Am I required to parse additional information into the shader or should I already have the necessary information to do this process? The image below describes the situation:
The hand to the left is a sprite not from an atlas. The hand on the right is a sprite from an atlas. I want the right hand to look the same as the hand on the left.
I am not that familiar with shaders yet, so I am reliant to using shaderforge. I am using the following shaderforge layout:
You probably already know this, but the fundamental problem is the output of your "UV Coords" node. The other nodes in your shader are expecting normalized UVs ranging from 0 to 1, but that's not what you're getting when you use the texture atlas.
I can think of two ways to solve that. They're both viable, so I'd recommend trying whichever one fits more cleanly into your workflow.
Add a second UV channel
It's easy to treat UV0 as the only UV channel, but for certain techniques it can be helpful to add multiple UV coords to each vertex.
As an example, lightmapping is a popular feature where each model has its own individual textures (diffuse/normal/etc), but each scene has a pre-baked lightmap texture that is shared between multiple models -- sort of like an atlas for lighting information. UVs for these will not match, so the lightmap UVs are stored on a second channel (UV1).
In a similar fashion, you could use UV0 for atlas UVs and UV1 for local UVs. That gives you clean input on the [0,1] range that you can use for that multiply effect.
Add material params
You could scale and offset the UVs so that they are normalized.
Before rendering, find the min and max values for the mesh's UV coords
Pass those values in as material parameters
Add shader nodes to scale and offset the input UV, such that the range is normalized
For example, you could add min to each UV (offset), then divide by max - min (scale).