Jump to content
  • Advertisement
Sign in to follow this  
Seabolt

Shadow Mapping general questions

This topic is 2490 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

Hey guys, I'm implementing a omni-directional shadow mapping algorithm, but I'm getting some weird artifacts, and I can't exactly explain them. So this may be an annoying post, but any help would be appreciated. Here's the offending code:

How I setup my cameras:

// Up vectors for the cameras
WVector upVecs[] =
{
{ 0.0f, 0.0f, 1.0f },
{ 0.0f, 0.0f, 1.0f },
{ 0.0f, 0.0f, 1.0f },
{ 0.0f, 0.0f, 1.0f },
{ 0.0f, -1.0f, 0.0f }, // Positive Y up vec for our "world up" vector
{ 0.0f, 1.0f, 0.0f } // Negative Y up vec for our negative "world up" vector
};
WVector forwardVecs[] =
{
{ 1.0f, 0.0f, 0.0f }, // Positive X
{ -1.0f, 0.0f, 0.0f }, // Negative X
{ 0.0f, 1.0f, 0.0f }, // Positive Y
{ 0.0f, -1.0f, 0.0f }, // Negative Y
{ 0.0f, 0.0f, 1.0f }, // Positive Z
{ 0.0f, 0.0f, -1.0f } // Negative Z
};
mOrthographicCamera = false; // We need a perspective camera
// Go through all our faces.
for( int currentFace = 0; currentFace < numCameras; ++currentFace )
{
// Get our camera
WCamera* camera = gCameraManager->GetCameraByHandle( mShadowMapFaces[ currentFace ].mCameraHandle );
ASSERT( camera );
// Set our up vectors
camera->SetUpVector( upVecs[ currentFace ].x, upVecs[ currentFace ].y, upVecs[ currentFace ].z );
camera->SetDestUpVector( upVecs[ currentFace ].x, upVecs[ currentFace ].y, upVecs[ currentFace ].z );
// Set our eye position and look at target
WVector eye = { mLight->GetPos()->x, mLight->GetPos()->y, mLight->GetPos()->z };
WVector forward = forwardVecs[ currentFace ];
WVector target = eye;
target += forward;
camera->SetEye( &eye );
camera->SetDestEye( &eye );
camera->SetTarget( &target );
camera->SetDestTarget( &target );
// Set our viewport size
camera->SetViewport( 0,0, mMapSize, mMapSize );
// Set our field of view to 90 degrees. We want to match each face edge perfectly.
camera->SetFov( 90.0f );
camera->SetTargetFov( 90.0f );
// Hard coded near far plane right now. We need a better solution someday.
camera->SetNearFar( 1.0f, mLight->GetAttenuation()->w);
// We're not orthographic, and we aren't trying to animate. Though we may want to in the future...
camera->SetOrthographicView(mOrthographicCamera);
camera->Pause();
}


Here's the code I use to output my shadow depth:

VS_OUT VertexShaderModel (VS_IN In)
{
VS_OUT Out;
Out.Position = mul (matWVP, In.Pos); // Transform position of vertex into screen
Out.WorldPos = mul( matW, In.Pos );
return Out;
}
float4 PixelShaderModel (VS_OUT In) : COLOR
{
return float4(saturate( length( In.WorldPos - PointLtPos[0].xyz ) / PointLtAttenuation[0].w ), 0, 0, 1);
}


And here's the code I use to test if I'm in the shadow (per pixel):

float3 pixelToLight = ShadowLtPos[ shadowMapIndex ].xyz - worldPos; //inObjPos is the pixel's position in world space
float pixelDepth = saturate( length(pixelToLight.xyz) / ShadowLtPos[ shadowMapIndex ].w ); //the depth of current pixel divided by the light's attenuation
pixelToLight.xyz = normalize( pixelToLight ); //compute attenuation factor
//sample the cubic shadow map using the inverse of light direction float
float shadowMapDepth = saturate( texCUBE(textureSampler3D, -pixelToLight ).x + 0.01f ); //do the depth comparison + a little shadow bias.
return pixelDepth >= shadowMapDepth;


I get some interesting artifacts with this, I'll attach images. Any obvious mistakes you guys see, or things I should consider?
The little triangles are my biggest worries. In PIX it shows that they are reading properly, they just seem to have the wrong values consistently. Also, my view frustums are actually covering those areas and generating proper depth maps for those areas. So I'm stumped.

Share this post


Link to post
Share on other sites
Advertisement
Sign in to follow this  

  • Advertisement
×

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

GameDev.net is your game development community. Create an account for your GameDev Portfolio and participate in the largest developer community in the games industry.

Sign me up!