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| Parallax mapping |
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whathappened Member since: 11/2/2005 From: Stockholm, Sweden |
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 Posted - 4/15/2006 8:18:31 AM |
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| I dont really know if this topic fits into the DirectX forum but I hope so since it's about shaders. I just wonder, what is parallax mapping? I know how to make bump mapping and some displacement mapping (to actual change the geometry) but what is parallax mapping? Anyone who has a good link where it's explained cause I couldnt find one |
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crazyishone Member since: 4/14/2006 From: Seattle, WA, United States |
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Posted - 4/15/2006 8:23:10 AM |
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| Here That gives a brief description of what parallax mapping is. |
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sirob GDNet+ Member since: 11/2/2002 From: Haifa, Israel. |
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Posted - 4/15/2006 8:26:47 AM |
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| Also, in case you are interested in an actual implementation, a Parallax Mapping sample has been recently added to the SDK samples. Grab the April '06 SDK to give it a go. Hope this helps. :) |
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whathappened Member since: 11/2/2005 From: Stockholm, Sweden |
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Posted - 4/15/2006 8:29:31 AM |
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| thank you. Is there any tutorials available somewhere? I've only seen short descriptions when trying to google :( |
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ET3D Member since: 10/24/2004 |
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Posted - 4/15/2006 7:21:52 PM |
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| Don't know about a tutorial, but if you google "parallax mapping site:ati.com" you should find a couple of docs. ATI's March SDK contains an article about this. |
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CadeF Member since: 8/16/2005 |
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Posted - 4/15/2006 10:39:55 PM |
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Its quite simple, actually. It only requires a heightmap texture for the shader pass.float3 vEye = -TBNViewDir; float fBumpScale = 0.05f; float2 vCoord = texCoord; float fDepth = tex2D(sHeightMapSampler, vCoord).w; float2 vHalfOffset = normalize(vEye).xy * (fDepth) * fBumpScale; fDepth = (fDepth + tex2D(sHeightMapSampler, vCoord + vHalfOffset).x) * 0.5; vHalfOffset = normalize(vEye).xy * (fDepth) * fBumpScale; fDepth = (fDepth + tex2D(sHeightMapSampler, vCoord + vHalfOffset).x) * 0.5; vHalfOffset = normalize(vEye).xy * (fDepth) * fBumpScale; return vCoord + vHalfOffset; Then, sample the diffuse texture and the normal texture using the returned coordinates. Basically, it samples the height map at the texture coordinate, and offsets the texture coordinates in the direction away from the viewer. I do 3 iterations to get good results. If you only do one, the effect is negligible. In these 2 screenshots, I have doubled the parallax amount to make the difference clearly visible.  No parallax mapping  Parallax mapping |
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jamesw Member since: 7/4/2005 From: Raleigh, NC, United States |
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Posted - 4/16/2006 2:35:35 AM |
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| Ah cool, I didn't think about multiple samples/calculations. Does that increase accuracy or create a larger offset? |
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Armadon XNA/DirectX MVP Member since: 4/20/2004 From: Durban, South Africa |
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Posted - 4/16/2006 5:20:36 AM |
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| Cadef, in the second screenshot if seems like your parallax mapping goes off to the left. Maybe a projection problem? |
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CadeF Member since: 8/16/2005 |
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Posted - 4/16/2006 7:39:05 AM |
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| Multiple samples increase accuracy. If you take 1 sample, it will look wrong. It is supposed to go off to the left, that is parallax mapping. It might seem a bit wrong, because I exaggerated the parallax scale to make the effect prominent. |
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whathappened Member since: 11/2/2005 From: Stockholm, Sweden |
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Posted - 4/16/2006 8:25:24 AM |
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| So parallax mapping is just about the texture coordinates? Would be great with a little more detailed explanation :) and does anyone know any links where I can find a simple texture and a nice parallax map to work with :) [Edited by - whathappened on April 16, 2006 7:25:58 AM] |
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ET3D Member since: 10/24/2004 |
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Posted - 4/16/2006 9:16:04 AM |
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Quote: The aforementioned SDK sample... |
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godmodder Member since: 11/5/2005 From: Genk, Belgium |
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Posted - 4/16/2006 9:29:34 AM |
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| www.ultimategameprogramming.com has a tutorial about parallelax mapping |
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whathappened Member since: 11/2/2005 From: Stockholm, Sweden |
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Posted - 4/16/2006 9:37:58 AM |
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| where on that page, the article list seems empty to me |
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ET3D Member since: 10/24/2004 |
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Posted - 4/16/2006 9:44:14 AM |
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| Yeah, that's one site I'm never going to visit again. |
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CadeF Member since: 8/16/2005 |
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Posted - 4/16/2006 10:37:35 AM |
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| Yes, parallax mapping is just about pushing texture coordinates away from the camera. How far it is pushed, depends on EyeVector * ParallaxMappingScale |
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whathappened Member since: 11/2/2005 From: Stockholm, Sweden |
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Posted - 4/16/2006 10:59:58 AM |
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| thanks :) |
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| All times are ET (US) |
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