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Black screen


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#1 Juliean   GDNet+   -  Reputation: 2437

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Posted 29 January 2012 - 09:40 AM

Hi,

I've recently been re-writing my first 3d game, because it was slow and a pain to develop with. However I've ran into a problem where I can't get a cube with a basic shader to show on the screen. The shader simply outputs a white color for the whole cube.. in theory. Practically, what I get is a total black screen. When clearing to any other color like red, I get a red screen. However, using the Nvidia PerfHUD to debug, I get this output:

Posted Image

So, the cube is actually there - adjusting the parameters of my view/world-matrices moves the cube around like it should. But why is the cube only showing up here and not in the actual game? Here is some code:

The shader:
float4x4 World : World;
shared float4x4 ViewProj : ViewProjection;

struct VS_INPUT
{
    float3  vPos		    : POSITION0;
    float2  vTex0		   : TEXCOORD0;
    float3  vNrm		    : NORMAL0;
    float3  vTan		    : TANGENT0;
    float3  vBin		    : BINORMAL0;
};

float4 mainVS(VS_INPUT i) : POSITION
{
    float4x4 WorldViewProj = mul(World, ViewProj);
    return mul(float4(i.vPos.xyz, 1.0), WorldViewProj);
}

float4 mainPS() : COLOR {
    return float4(1.0, 1.0, 1.0, 1.0);
}

technique technique0 {
    pass p0 {
        VertexShader = compile vs_3_0 mainVS();
        PixelShader = compile ps_3_0 mainPS();

        CullMode = ccw;
        ColorWriteEnable = red | green | blue | alpha;
    }
}
//mesh render method
void Mesh::Render(void)
{
    m_lpDevice->SetStreamSource(0, m_lpVertexBuffer, 0, sizeof(D3DVERTEX));
    m_lpDevice->SetIndices(m_lpIndexBuffer);
    m_lpDevice->SetVertexDeclaration(m_lpVertexDeclaration);
    m_lpDevice->DrawIndexedPrimitive(D3DPT_TRIANGLELIST, 0, 0, m_nNumVertices,0,m_nNumVertices/3);
}


//render model with mesh,material and effect
void Model::Render(void)
{
    D3DXMATRIX Identity;
    D3DXMatrixTranslation(&Identity,1.0f, 1.0f, 1.0f);
    m_pEffect->SetMatrix("World", Identity);
    m_pEffect->Begin();
    m_pMaterial->Use(m_pEffect);
    m_pEffect->BeginPass();
    m_pMesh->Render();
    m_pEffect->EndPass();
    m_pEffect->End();
}

void Graphics3D::Render(Camera* pCamera)
{
    D3DXMATRIX Matrix = pCamera->GetViewProjectionMatrix();
    m_EffectSpace.GetPoolEffect(L"Models")->SetMatrix("ViewProj",Matrix);
    for(vector<Model*>::iterator ii=m_vModels.begin();ii!=m_vModels.end();++ii)
    {
        (*ii)->Render();
    }
}

//camera class

Camera::Camera(void) : m_vPosition(10.0f, 0.0, 0.0), m_vLookAt(0.0f,0.0f,0.0f),m_vUp(0.0f,1.0f,0.0f)
{
    D3DXMatrixLookAtLH(&m_mView, &m_vPosition, &m_vLookAt, &m_vUp);
    D3DXMatrixPerspectiveFovLH(&m_mProjection, D3DX_PI/4, 2560.0f / 1600.0f, 0.5f, 5000.0f );
    D3DXMatrixMultiply(&m_mViewProjection,&m_mView,&m_mProjection);
}

Camera::~Camera(void)
{
}

D3DXMATRIX Camera::GetViewProjectionMatrix(void)
{
    return m_mViewProjection;
}

This is most of the code involved into rendering the mesh. Using the directx debug runtime, I get no errors or warning, and DrawIndexedPrimitve succeedes.

Only hint I have is that PIX shows me something like this for the call to set the ViewProjection-Matrix:

Posted Image

Other than the mesh obviously rendered correctly on the right side, why is there a NULL in the SetMatrix-Call? The matrix I pass is valid, but Nvidia PerfHUD also shows that the constants for the ViewProjection-Matrix are all 0. On the other hand, why does but PIX and PerfHUD show the mesh drawn correctly, at least as wireframe?

I am really at the end of my knowledge, does somebody else see any obvious mistake here?

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#2 bzroom   Members   -  Reputation: 646

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Posted 29 January 2012 - 11:16 PM

Check your zbuffer settings. I dont see any clear depth or ztest direction specified here. It appears that all your fragments are being zrejected. Vertex shader and draw call code obviously works correctly.

#3 turch   Members   -  Reputation: 590

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Posted 30 January 2012 - 08:13 AM

In your call to IDirect3DDevice9::Clear(), for the third parameter, you only tell it to clear the color (D3DCLEAR_TARGET), you need to pass in
D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER

and also D3DCLEAR_STENCIL if you are going to use the stencil buffer.

By the way, in Pix you can also right click on a pixel in the render window and click "debug pixel" or something similar, and it will show you all of the times the pixel was processed, including the output color / opacity, if it passed or failed the depth and stencil tests, and from there you can also debug the pixel shaders the same way that you can debug vertex shaders.

#4 Juliean   GDNet+   -  Reputation: 2437

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Posted 31 January 2012 - 01:04 AM

Thanks,

Clearing the z-buffer solved the issue. I don't know why I forgot to do so in the first place..

Thanks for the tip with PIX too. I'm just starting
with it, as my old game always kept crashing when using it.




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