Texture Projection Issue

Okay, I've kinda given up on this. I can't get it to work. Does anyone have any alternative or better methods for doing a reflection?

You aren't setting the other 4 parts of your matrix, the mat_14...mat_44, so they most likely contain garbage.

Oh okay. Can you tell me what the parts of the matrix are? I know how to do the D3DX functions but i'm not really sure about what the values are.

Those matrix values look pretty strange to me, but I haven't seen the bigger picture. As SimmerD suggested, you should start off by completing the matrix initialisation:

mat._11 = 0.8f; mat._12 = 0.0f; mat._13 = 0.0f; mat._14 = 0.0f;mat._21 = 0.0f; mat._22 = 0.8f; mat._23 = 0.0f; mat._24 = 0.0f;mat._31 = 0.5f; mat._32 =-0.5f; mat._33 = 1.0f; mat._34 = 0.0f;mat._41 = 0.0f; mat._42 = 0.0f; mat._43 = 0.0f; mat._44 = 0.0f;

Tell us exactly what the render-texture looks like and we may be able to be more precise.

By the by, are you using a point mip-filter for the terrain? It looks very grainy. Maybe

g_pD3DDevice->SetSamplerState(0, D3DSAMP_MIPFILTER, D3DTEXF_LINEAR);

would make things prettier.

Admiral

Okay, IU completed the matrix but it does not seem to make a difference.

Thanks for that mip thing, it helps.

Heres my render target reflection texture:



Heres the scene:



Thanks.

It seems you took me a little more literally than I expected [rolleyes]. The pictures are helpful, but better would be if you could tell us what changes you make to the world-view-projection matrix between rendering the scene and the water texture.

It's a little difficult to tell from a static image, but the texture you posted looks kind of 'backward'. Are you remembering to swap the cull-mode for the reflected render pass?

Admiral

This is all that I do before rendering to the texture:



and then to project the texture i use this:


If you mean setting the culling to D3DCULL_CW by swapping the cull mode, I just tried that but it did not seems to have changed it but now there are a whole bunch of little triangle strips.

Okay. Your code is a mystery to me. There seem to be quite a few magic numbers thrown about. From what source are you adapting your it (especially the projection matrix)? I'm in a little deep as things stand, but I have a couple of comments anyway.

Don't disable the cull-mode switch call. Even if the results look better without it, you won't get the right results unless it's in place.

While debugging, you should disable the clipping plane. While it's necessary in release code to prevent ghost reflections in non-monotonic terrains, it's one more thing to go wrong when testing.

You may find it helpful to write some code to render the reflected texture in the corner of the screen in real-time. This way, you can be sure that the render-texture is correct.

D3DXVECTOR3 vPoint(0,2.0f*waterHeight,0);D3DXVECTOR3 vNormal(0,(2.0f*waterHeight)+1.0f,0);

- looks very suspicious to me. Why are you multiplying the water's height by two, and why does the height even feature in the normal? Provided that the water is guaranteed to lie in the xz plane, a simple constant y-axis reflection matrix will suffice:

D3DXVECTOR3 matReflect;D3DXMatrixIdentity(&matReflect);matReflect._22 = -1.0f; // Or _33, if 'z' is up.

Admiral

Quote:

Original post by TheAdmiral Okay. Your code is a mystery to me. There seem to be quite a few magic numbers thrown about. From what source are you adapting your it (especially the projection matrix)? I'm in a little deep as things stand, but I have a couple of comments anyway.

I got the matrix from the directx sample, "Bump Waves" because when I tried a making a simple matrix it didn't work.

Quote:

Don't disable the cull-mode switch call. Even if the results look better without it, you won't get the right results unless it's in place.

Okay.

Quote:

D3DXVECTOR3 vPoint(0,2.0f*waterHeight,0);D3DXVECTOR3 vNormal(0,(2.0f*waterHeight)+1.0f,0); - looks very suspicious to me. Why are you multiplying the water's height by two

The terrain is scaled so i scale the water height too.

Quote:

, and why does the height even feature in the normal? Provided that the water is guaranteed to lie in the xz plane, a simple constant y-axis reflection matrix will suffice:

Wow, your right. I didn't even think about that. Thanks.

Thanks, that helped. My problem now seems to be that the texture is not being flipped upside down. Is there any way I can do that?

Heres an image:

I think, the matrix you're using is wrong. Try to use following:

mat._11 = 0.5f; mat._12 = 0.0f; mat._13 = 0.0f; mat._14 = 0.0f;
mat._21 = 0.0f; mat._22 =-0.5f; mat._23 = 0.0f; mat._24 = 0.0f;
mat._31 = 0.0f; mat._32 = 0.0f; mat._33 = 1.0f; mat._34 = 0.0f;
mat._41 = 0.5f; mat._42 = 0.5f; mat._43 = 0.0f; mat._44 = 1.0f;

I use this matrix in my application and it works (but i'm using shaders for water simulation). Here is the screenshot from my application:



[Edited by - Alex-R on February 26, 2007 5:14:21 AM]

Cool, thanks! That works well:

Hello, Im new to D3D and was looking for tut's like this could you post or send me a copy of you code or if you have a web page a link to this.
thanks. looks good any way

This is an article about water rendering:
http://www.gamedev.net/reference/articles/article2138.asp

Yeah, if you still want my code, just private message me your email address.