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Author Topic: Yet Another "Possibly" Stupid Question  (Read 1644 times)

Old Codger

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Yet Another "Possibly" Stupid Question
« on: August 12, 2021, 04:10:25 pm »

Trigger warning: I may well be the world's oldest 5-year-old so I have a bajillion questions.

This may well be a stupid question but unfortunately the only way to clear the "question" flag in my head is to ask the question.  ;) (Please note that if this has been covered elsewhere a simple link to that info will more than suffice.)

So here goes:
I've been wondering about all those nifty places to put textures that show up on the "Surface Texture Editor" dialog box. "Diffuse" I know about. "Bump Map" I've experimented with and understand to a degree. I think I have even figured out "Trans", in fact am looking at modelling a spaceship drive flame using a trans texture that goes from 255 white to 0 black to allow the "flame" to fade out.

1. "Ambient" - Why and under what circumstances would I want to put a texture in the "Ambient" field? I am sorta aware of the relationship between "Ambient" and "Specular" in the materials dialog but I can get my textures and decals to show up okay merely by specifying a texture in "Specular". What does doing something with "Ambient" do for me? Does it need to be the same texture as "Specular"? What happens if I put different textures in those two slots?

2. "Emissive" - What effect would specifying some sort of texture in that field have? Would that produce the effect of light but only in certain circumstances? I know programmers well enough to figure Stephen did not throw that in there just for grins and giggles.

3. "Normal Map" - I know what "normals" are - sorta - and know how to use a bump map to create the illusion of geometry when it isn't really there. What is a "Normal Map" and what effect does it have?

4. "Env. Map" - I vaguely recall reading about the "Env. Map" in the tutorial about producing reflections. Since we cannot actually reflect the background, how does specifying a texture in the "Env. Map" help me?

Final question: Short of applying a texture to a specific face (or group of faces) is there a way to tell Anim8or to generate UV coordinates for a given object/mesh? Is there a way to get Anim8or to show me the UV map of a given object/mesh? If not does anybody know of a good, CHEAP (preferably free) UV mapper? I find myself increasingly needing to get into texturing things and so need to generate texture maps. Also, back when I was heavily into MS Flight Simulator and creating my own liveries for my plane models, it was possible to apply a portion of an existing texture to a specific part of a model. Any chance Anim8or has a way to do that? Alternatively, just being able to produce a UV map for a given object would be highly useful. If I had a graphic of the UV map I could use that to "paint" various parts of a model from a master texture. PSE and I are old friends at layering texture files.

I'll shut up now and thank anyone who answers (or even reads my scrawl) in advance. You folks are the best bar none!
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Claude

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Re: Yet Another "Possibly" Stupid Question
« Reply #1 on: August 12, 2021, 07:23:46 pm »

3. "Normal Map" A normal is a unity vector perpendicular to a surface. It gives the orientation of the surface  at a point and is used to calculate lighting at that point. The rgb value of each pixel of a Normal Map gives a normal value  for this pixel.
vec3 rgb_normal = normal * 0.5 + 0.5; // transforms from [-1,1] to [0,1]  Reverse the formula to get the normal from rgb.
Similar to Bump Map.
Examples here:
https://www.anim8or.com/smf/index.php/topic,5341.0.html
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Claude

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Re: Yet Another "Possibly" Stupid Question
« Reply #2 on: August 12, 2021, 07:58:26 pm »

Ambient is what you see when there's no specific light present (point, spot or infinite).If you're in a closed cavern without light inside, ambient is zero. If you're
in a field covered with snow  ,surrounded by a forest, with
a cloudy sky and no moon, even if there's no light, you still see something. Then, you would use the same texture as for diffuse , but with a low ambient factor.
You would see only the ambient texture with no contribution by the diffuse texture.
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Claude

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ENSONIQ5

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Re: Yet Another "Possibly" Stupid Question
« Reply #4 on: August 13, 2021, 02:39:58 am »

The "Emissive" channel is often called "Glow" in other systems.  In basic terms, this channel controls the illumination of an object independently of any light sources in the scene, so it can be used to make something appear to glow.  On the attached image 'IceTruckA038', examples of objects with emissive qualities can be seen such as the yellow route markers and the green lights on their bases, as well as the glowing lights on the vehicle (not the light cones from the headlights).

Textures loaded to this channel can be used to create glowing areas, such as the control panel buttons and screens on the attached image 'SednaGuardhouseScreens1'.

EDIT: Note that emissive objects and textures don't actually cast illumination on other things, they just appear to glow.  Pairing an emissive object with an actual light source gives the appearance that the glowing object is casting light on things.
« Last Edit: August 13, 2021, 02:58:00 am by ENSONIQ5 »
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ENSONIQ5

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Re: Yet Another "Possibly" Stupid Question
« Reply #5 on: August 13, 2021, 02:54:52 am »

Regarding UV mappers I use LithUnwrap which has a free downloadable version, but there are others.  Google is your friend in that respect.  Having said that, Anim8or's built-in UV control tool is actually really useful, for example the glowing panels and switches on the console in the second image above were all added to the object and aligned with it before the object was exported for rendering (mainly for consistency I render most things outside Anim8or which is a shame really, since Anim8or renders always seem to look richer somehow).

Re your comment "Since we cannot actually reflect the background, how does specifying a texture in the "Env. Map" help me?", I should point out that ART materials are absolutely capable of reflecting the background using the ART renderer.  ART materials are complex but seriously powerful, the manual is very detailed on these and is definitely compulsory reading before tackling them!

Regarding what happens when placing different textures in different channels, I would recommend creating a single scene with a single object and light source and experiment away, rendering the same scene with materials in each channel and swapping them about for each render.  It really is the best way to get to grips with how the different material channels work.
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Steve

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Re: Yet Another "Possibly" Stupid Question
« Reply #6 on: August 13, 2021, 04:51:01 pm »

Here's a project that shows how to use textures in many ways.
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Old Codger

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Re: Yet Another "Possibly" Stupid Question
« Reply #7 on: August 14, 2021, 11:10:21 am »

Thank you, Steve. Gonna have to spend some time studying that project file and cogitating on all you've condensed into those few simple objects.

Thanks to all who took the time to read and answer my questions. Seems I'm asking college level questions in the 2nd grade. Typical of me. At least I'm not afraid to admit my ignorance LOL. ;)

OT: Seems like I keep finding new uses for the topo knife. Which is interesting considering I used to couldn't see a use for it at all. Now I KNOW I did the right thing by deciding to concentrate on Anim8or (in which I at least some time in the past had developed at least a minimal facility) as opposed to starting from scratch in, for example, Daz's Hexagon. This way I can at least produce SOMEthing even while learning. I used to think I was operating at a journeyman level but now believe I am operating - at best - on a mid-apprentice level. The more I learn the more I come to appreciate you folks in the Anim8or community and in the greater 3D modeling/CGI world at large. Have to admit my biggest failure at the moment is failure of imagination. If I cannot get a clear picture of what I want to build I have no hope of building it. Hat's off to you folks and especially to Stephen. You are a pure dee wonder, young man, and don't let anybody tell you different.
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mrbeaver.07

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Re: Yet Another "Possibly" Stupid Question
« Reply #8 on: August 15, 2021, 04:44:28 am »

Here's a project that shows how to use textures in many ways.
Finally, I understood what is the difference between types of textures.
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