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Water Reflection

Started by Grigou Sep 1, 2008 at 7:17 AM 1 replies 1.2k views

Original Post

Sep 1, 2008 at 7:17 AM

Hi, I've been working on a HLSL water shader for my engine, everything is working fine except when it comes to reflecting the skybox.... I am using render to textures and user clip planes to generate the reflection and refraction textures. Landscape and meshes are reflected perfectly but the skybox doesn't appear on the reflection texture. I think the problem is rendering the skybox with the reflection view matrix... This is how I render the skybox :


D3DXMatrixTranslation(&mWorld,CDXObjects::Instance().getCameraPosition()->x,CDXObjects::Instance().getCameraPosition()->y,CDXObjects::Instance().getCameraPosition()->z);
CDXObjects::Instance().setWorldMatrix(mWorld);  
CDXObjects::Instance().getDevice()->SetFVF(SBVertex::FVF);
CDXObjects::Instance().getDevice()->SetStreamSource(0,vBuffer,0,sizeof(SBVertex));	TLfx2->SetMatrix(hWorldViewProj,CDXObjects::Instance().getWorldViewProj());
TLfx2->Begin(NULL,0);
for (unsigned int i=0;i<6;++i)
{
	TLfx2->BeginPass(0); 
        CDXObjects::Instance().getDevice()->SetTexture(0,SBTex);
   CDXObjects::Instance().getDevice()->DrawPrimitive(D3DPT_TRIANGLESTRIP,i*4,2);
	TLfx2->EndPass(); 
}
TLfx2->End();

For reflection the view matrix is replaced by the reflection view matrix. These are the render states for the shader :


technique main
{
	pass p0
	{
		vertexshader = compile vs_1_1 VShader();
		pixelshader = compile ps_2_0 PShader();
		LIGHTING = FALSE;
		ZENABLE = FALSE;
		ZWRITEENABLE = FALSE;
		CULLMODE = NONE;
	}
}

If someone has an idea.... Thanks

jollyjeffers

Sep 1, 2008 at 11:22 AM

Have you checked the winding order? I remember having a similar sounding problem when I implemented this algorithm - the reflected geometry was getting culled due to being back-facing. Try D3DRS_CULLMODE = D3DCULL_NONE to see if it appears.

Failing that, stepping through in PIX can be very useful to figure out when and why something isn't being rendered.

hth
Jack

Grigou

Sep 2, 2008 at 6:19 AM

Hi,
First of all, thanks for your reply.
So I tried messing arround with culling but it didn't change anything...
I think the problem comes from the reflection view matrix and translating the skybox for it to follow the player.
This is how I calculate the reflection view matrix :

void CCamera::computeReflectionViewMatrix(){	D3DXPLANE p;	D3DXMATRIX * tmp = DXObjects::Instance().getViewMatrix();        D3DXMatrixIdentity(&mReflecView);D3DXPlaneFromPointNormal(&p,&D3DXVECTOR3(0.0f,CDXObjects::Instance().getWaterHeight(),0.0f),&D3DXVECTOR3(0.0f,1.0f,0.0f));	D3DXMatrixReflect(&mReflecView,&p);	mReflecView = mReflecView * (*tmp);	CDXObjects::Instance().setReflectionViewMatrix(mReflecView);  }

Thanks

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