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What are shaders? What do they do? Uses?
#46665
05/26/05 04:58
05/26/05 04:58
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Joined: Feb 2003
Posts: 6,818
Minot, North Dakota, USA
ulillillia
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Can someone explain, in more depth, what shaders are, what do they do, what their uses are, and other stuff? I looked at some of the screenshots in the shader index and some of it appears to be a regular skin image. It seems just like a model with a complex skin arrangement which makes more more confused on what shaders are. Is that what a shader is? A skin image? Some of you can make extremely high-quality art work, there's no apparent need for shaders if shaders aren't just a skin image. Also, what is an HLSL shader? What does my graphics card support (I have Radeon 9600 XT)? I'm very confused about shaders and what they are, what they do, what they're for, etc..
Edit: also, what are vertex and pixel shaders? What's the pros and cons between the 2?
Last edited by ulillillia; 05/26/05 05:14.
"You level up the fastest and easiest if you do things at your own level and no higher or lower" - useful tip
My 2D game - release on Jun 13th; My tutorials
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Re: What are shaders? What do they do? Uses?
[Re: FeiHongJr]
#46667
05/26/05 06:24
05/26/05 06:24
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Joined: Feb 2003
Posts: 6,818
Minot, North Dakota, USA
ulillillia
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Yeah, you can make fur with a skin image too and do toon shading (the black lines I believe) with a skin. I still don't understand. Also, what's bump mapping? Will this increase the poly count drastically? When I think of bumps, I think of small humps and things in the view, but to do that, for the size of my worlds, I'd need a graphics card a billion times faster than the one I've got as I don't think video cards nowadays can even support 50 terapolys per second....
"You level up the fastest and easiest if you do things at your own level and no higher or lower" - useful tip
My 2D game - release on Jun 13th; My tutorials
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Re: What are shaders? What do they do? Uses?
[Re: ulillillia]
#46668
05/26/05 06:33
05/26/05 06:33
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Joined: Feb 2003
Posts: 6,818
Minot, North Dakota, USA
ulillillia
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I don't really like the way WIKI is designed, so I never look at it. Designed as in having to enter username and password. It bothers me so I'm not going to look at it. I looked at it before (don't remember when), but ran into this same thing and it bothered me so I just turned away. I looked at that "shader index" thread at the top of this forum and it seems so much that it's just a skin image that someone who's more talented in art than I am, accomplished.
Here's an analogy:
true newbie to computers : very frustrating to use them :: me to shaders : very confused about them
Hopefully you know what analogies are (no, you don't need to fill in the blank as from in school, it's already done).
"You level up the fastest and easiest if you do things at your own level and no higher or lower" - useful tip
My 2D game - release on Jun 13th; My tutorials
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Re: What are shaders? What do they do? Uses?
[Re: ulillillia]
#46669
05/26/05 07:01
05/26/05 07:01
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Joined: Oct 2004
Posts: 493
WHURL
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what are shaders? Quote:
A shader is basically the set of rules on how an object looks. The rules can be almost anything but there are are a lot of established routines to make this task a lot more simple for us. There are rules that can describe how objects react to lighting, functions to read texturemaps, fetch reflections and refractions and so on. Shaders can be formulated to look like real physical materials or shaders can be written to look like cartoon surfaces or even output technical data, such as distance from camera.
Shaders are also not limited to surface colour only - there are different type of of shaders: shaders can manipulate the shape of an object (displacement shaders), describe the atmosphere (fog shaders) and how light and shadow is cast (light shaders and shadow shaders).
The basic concepts behind shaders
Quote:
Basic surface shaders usually can be split up into a few concepts. The resulant colour of a surface is a mathematical combination of the following properties.
* illumination- ambient, diffuse, specular, sub-surface and indirect
* raytracing- reflections, refractions and related phenomena like fresnel
* texturemapping- procedural and map-based colourisation of a surface
* bump mapping- this is how we can affect how the lighting affects a surface by "fooling" the renderer into thinking that your object has parts of it facing in different directions. this give the illusion of more modeled detail in your geometry.
Here's an intro to High Level Shading Language (HLSL).
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Re: What are shaders? What do they do? Uses?
[Re: WHURL]
#46670
05/26/05 07:25
05/26/05 07:25
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Joined: Oct 2003
Posts: 2,628
IL,US
FeiHongJr
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Ok took a couple of the pics from the wiki to show you. These are the toon and fur shaders.Both would be very difficult if not impossible without shaders. You could as you said use black outlines for your chacter but only if it would be seen from on angle at a time in a 3d enviroment chances are your chacter will be changing positions all the time so you would have to have multiple skins in order to acheive something similliar.The fur shader would be very very difficult to achieve with a skin in my opinion.   You have to think that each angle your chacter can be viewed from would change the way the chacter would look and change the way the shading needs to be applied so would take a lot of skins not to mention coding to get something to look decent. and bumpmapping to my knowledge and expeirence with it in other programs will basically give more depth to you other wise flat walls. Say you have a brick wall texture. With bumpmapping you could acctually make it look as tho the bricks stand further out then the mortar. which could probally be achieved with a good texture. but im sure theres many other reason why a shader would be a better way to go. these are just my opinions and thoughts on it tho 
Last edited by FeiHongJr; 05/26/05 07:45.
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Re: What are shaders? What do they do? Uses?
[Re: WHURL]
#46671
05/26/05 07:27
05/26/05 07:27
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Joined: Feb 2003
Posts: 6,818
Minot, North Dakota, USA
ulillillia
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Okay, then, what does my video card support then, if it supports shaders at all? I have Radeon 9600 XT. It seems, though, that a lot of stuff from shaders can simply be done with a skin image so what's the point in having a shader in this case? A lot of my textures have black with random amounts of alpha which gives a bump-like feel. My platforms are an example of this as well as the buildings, sandy shore on the beach, etc.. I don't have shaders, I'm using a skin image for the bump effects. Basically, all I do is use the add noise feature, use color reduction to get 2 channels per color (allowing for 8 different colors), then, in the GIMP, import this image as a layer, turn a color into black, set the first alpha to 0, do the next color, turn it to black, make the alpha at 32, do the next at 64 and so on. Then I do a mass-color erase at either 75 or, sometimes, 87.5 to simulate the roughness. However, this technique has limits, easily noticed with my beach. I could almost just use a 2x2 skin for the platforms (except the goal and start platforms) and, if it's possible, apply the roughness effect to it.
If there was another way to apply the roughness at the 1:1 resolution (I'd prefer 2 pixels per quant myself), I could have smaller skin sizes (not the huge 1024x1024 textures I use very often) which could, in turn, allow for a lot more options.
"You level up the fastest and easiest if you do things at your own level and no higher or lower" - useful tip
My 2D game - release on Jun 13th; My tutorials
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Re: What are shaders? What do they do? Uses?
[Re: ulillillia]
#46672
05/26/05 07:32
05/26/05 07:32
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Joined: Oct 2003
Posts: 2,628
IL,US
FeiHongJr
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Code:
gpu | v.s. | p.s. | t&l | tex | Max. texture size
Radeon 9600 Series | 2.0 | 2.0 | yes | 8 | 2048x2048x1024
Pretty sure that card would fall in to this category ... Nice card wanna trade  I wish i could find or show you some examples but my card doesnt support too much and i havent successfully used bump mapping so not sure it even supports that
Last edited by FeiHongJr; 05/26/05 07:35.
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Re: What are shaders? What do they do? Uses?
[Re: ulillillia]
#46673
05/26/05 07:35
05/26/05 07:35
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Joined: Feb 2003
Posts: 6,818
Minot, North Dakota, USA
ulillillia
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@ FeiHongJr: I have a brick texture for the walls in my restaurant (if I were to use something else, it'll mean having to use a skin size of 2048x1024 (to keep the 1 pixel per quant resolution). Take out the roughness, I could stick with a 256x256 texture without too much trouble (though it'll get stretched to 4x the size meaning 4 quants per pixel). But, without the roughness, it'll become extremely difficult to judge distances. The bricks are 256 quants wide by 128 quants tall (6 inches by 3 inches). Yet, even with the roughness, it's still difficult to tell where one wall ends when another one is in the background (the same goes for my city's buildings)....
"You level up the fastest and easiest if you do things at your own level and no higher or lower" - useful tip
My 2D game - release on Jun 13th; My tutorials
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Re: What are shaders? What do they do? Uses?
[Re: FeiHongJr]
#46674
05/26/05 07:51
05/26/05 07:51
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Joined: Feb 2003
Posts: 6,818
Minot, North Dakota, USA
ulillillia
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Quote:
Code:
gpu | v.s. | p.s. | t&l | tex | Max. texture size
Radeon 9600 Series | 2.0 | 2.0 | yes | 8 | 2048x2048x1024
Pretty sure that card would fall in to this category ... Nice card wanna trade
I wish i could find or show you some examples but my card doesnt support too much and i havent successfully used bump mapping so not sure it even supports that
Huh!? a 1024-bit texture!? No way! Also, what's with the v.x., p.s., t&l, and the tex stuff?
I paid $140 for that card and it doesn't seem as good as I was hoping for. The output I'm getting from the card isn't anywhere near what the specs on ATI's website say:
Code:
ATI Product Comparison
Product Name RADEON 9600 XT
ASIC RADEON 9600
Technology Features
SMARTSHADER™ 2
SMOOTHVISION™ 2.1
FULLSTREAM™ Real, DivX
Adaptive De-Interlace VIDEOSHADER™
HYDRAVISION™ Yes
Hardware MPEG Encode Assist -
Specifications
Bus Type AGP 4X, 8X
Memory Amount (MB) 128
Memory Type DDR1
Memory Interface 128-bit
Memory Clock Speed (MHz) 300
Engine Clock Speed (MHz) 500
Pipelines 4
Pixel Fillrate 2.0 Gpixels/sec
Geometry Rate 250 MTriangles
Display Support
VGA Yes
DVI Yes
Dual Monitor Display Yes
YPrPb Out for HDTV w/adapter optional
S-Video Out Yes
Composite Out w/adapter optional
Multimedia Support
S-Video In -
Composite In -
TV Tuner -
FM Tuner No
DTV Tuner
Remote Control Included -
EAZYLOOK -
Audio Out -
S/PDIF Out -
The site says that I should be getting 250 million triangles per second, but I'm only getting a tenth of that. Also, the box has a memory clock speed of 600 MHz, and here it says 300 MHz. I don't know what the memory interface thing is nor what pipelines are.
I don't know what the pixel fill rate thing is, but, in my game, I've got way more than 2 gigapixels even on the screen and I'm getting 30 fps....
"You level up the fastest and easiest if you do things at your own level and no higher or lower" - useful tip
My 2D game - release on Jun 13th; My tutorials
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Im about to attempt bump mapping yet again so wish me luck