# DX11 Problem with displaying Cube in DX11

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Hey Guys,

I'm developing a game using DirectX 11, so I started of by creating the basic structure and tried to render a simple cube.

The problem is that the cube is somehow stretched vertically over the window and the colors (red for top / blue for bottom) are mixed:

I checked everything via the Graphics Debugger and all the values seem to be okay, but the cube already looks strange in the vertex shader:

I thought there might be a problem with the projection matrix but it looks okay to me:

m_ProjectionMatrix = XMMatrixPerspectiveFovLH(0.25f*3.14159265359, (float)m_pWindow->GetHeight() / (float)m_pWindow->GetWidth(), 1.0f, 1000.0f);


Has anyone had the same problem or does anybody know how I could solve this problem?

Cranberry

Edited by Cranberry

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Are you setting the viewport properly?

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D3D11_VIEWPORT viewPort;
viewPort.TopLeftX = 0.0f;
viewPort.TopLeftY = 0.0f;
viewPort.Width = static_cast<float>(pWindow->GetWidth());
viewPort.Height = static_cast<float>(pWindow->GetHeight());
viewPort.MinDepth = 0.0f;
viewPort.MaxDepth = 1.0f;



Looks fine to me.

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cbuffer cbPerObject
{
matrix worldMatrix;
matrix viewMatrix;
matrix projectionMatrix;
};

struct VertexIn
{
float3 Pos : POSITION;
float4 Color : COLOR;
};

struct VertexOut
{
float4 PosH : SV_POSITION;
float4 Color : COLOR;
};

VertexOut VS(VertexIn vin)
{
VertexOut vout;
vout.PosH = mul(float4(vin.Pos, 1.0f), worldMatrix);
vout.PosH = mul(vout.PosH, viewMatrix);
vout.PosH = mul(vout.PosH, projectionMatrix);
vout.Color = vin.Color;
return vout;
}

float4 PS(VertexOut pin) : SV_TARGET
{
return pin.Color;
}


Yeah I transpose all three of them.

Here's my Render function, maybe you can spot a mistake:

void Game::Render()
{
m_pRenderSystem->PreRender();

//Set geometry buffers
UINT stride = sizeof(Vertex);
UINT offset = 0;

m_pRenderSystem->GetDeviceContext()->IASetVertexBuffers(0, 1, &m_pCubeVertexBuffer, &stride, &offset);
m_pRenderSystem->GetDeviceContext()->IASetIndexBuffer(m_pCubeIndexBuffer, DXGI_FORMAT_R32_UINT, 0);

//Set constant buffer
D3D11_BUFFER_DESC cbPerObjectDesc;
cbPerObjectDesc.Usage = D3D11_USAGE_DYNAMIC;
cbPerObjectDesc.ByteWidth = sizeof(cbPerObject);
cbPerObjectDesc.BindFlags = D3D11_BIND_CONSTANT_BUFFER;
cbPerObjectDesc.CPUAccessFlags = D3D11_CPU_ACCESS_WRITE;
cbPerObjectDesc.MiscFlags = 0;
cbPerObjectDesc.StructureByteStride = 0;

m_pRenderSystem->GetDevice()->CreateBuffer(&cbPerObjectDesc, 0, &m_cbPerObject);

D3D11_MAPPED_SUBRESOURCE mappedResource;
cbPerObject* dataPtr;
unsigned int bufferNumber;

dataPtr = (cbPerObject*) mappedResource.pData;

XMMatrixTranspose(m_WorldMatrix);
XMMatrixTranspose(m_ViewMatrix);
XMMatrixTranspose(m_ProjectionMatrix);

dataPtr->worldMatrix = m_WorldMatrix;
dataPtr->viewMatrix = m_ViewMatrix;
dataPtr->projectionMatrix = m_ProjectionMatrix;

m_pRenderSystem->GetDeviceContext()->Unmap(m_cbPerObject, 0);

// Set the position of the constant buffer in the vertex shader.
bufferNumber = 0;

// Finanly set the constant buffer in the vertex shader with the updated values.
m_pRenderSystem->GetDeviceContext()->VSSetConstantBuffers(bufferNumber, 1, &m_cbPerObject);

//Draw cube
m_pRenderSystem->GetDeviceContext()->DrawIndexed(36, 0, 0);

m_pRenderSystem->PostRender();
}


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vout.PosH = mul(float4(vin.Pos, 1.0f), worldMatrix);
vout.PosH = mul(vout.PosH, viewMatrix);
vout.PosH = mul(vout.PosH, projectionMatrix);

and

XMMatrixTranspose(m_WorldMatrix);

Should give you the deriered multiplication order. (im not in touch with XMMath)

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XMMatrixTranspose will return the transpose of the matrix, it won't modify the matrix that's passed in as its argument. So you either need to assign the result to a temporary variable, or assign the result directly to your mapped constant buffer data.

As the above poster suggested, you can tell the shader compiler to expect row-major matrices which will allow you to skip the annoying transpose step in your C++ code. To do this you can use the pragma that he mentioned, or you can add "row_major" to the declaration of the matrix in your HLSL constant buffer definition. There are also flags that you can pass to fxc.exe or D3DCompile that will achieve the same thing.

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Thank you so much!

I was thinking of the old D3DXTransposeMatrix which modified the matrix via a reference.

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