Question

I am attempting to apply a perspective transformation in DirectX-11 to a rendered cube centered at the origin (0, 0, 0), and with edges that span 1.0 unit (-0.5 to 0.5). However, I am not seeing anything rendering. I have tried the following:

shaders.hlsl

cbuffer VSHADER_CB
{
    matrix mWorld;
    matrix mView;
    matrix mProj;
};

struct VOut
{
    float4 position : SV_POSITION;
    float4 color : COLOR;
};

VOut VShader(float4 position : POSITION, float4 color : COLOR)
{
    VOut output;

    output.position = mul(position, mWorld);
    output.position = mul(output.position, mView);
    output.position = mul(output.position, mProj);
    output.color = color;

    return output;
}

...

void InitConstantBuffer()

...
D3DXVECTOR3 position(0.0f, 0.0f, -5.0f);
D3DXVECTOR3 lookAt(0.0f, 0.0f, 0.0f);
D3DXVECTOR3 up(0.0f, 1.0f, 0.0f);

D3DXMatrixIdentity(&(cbMatrix.mWorld));
D3DXMatrixLookAtLH(&(cbMatrix.mView), &position, &lookAt, &up);
D3DXMatrixPerspectiveFovLH(&(cbMatrix.mProj), 70.0f, (FLOAT)(width / height), 1.0f, 100.0f);

D3D11_BUFFER_DESC cbd;
ZeroMemory(&cbd, sizeof(D3D11_BUFFER_DESC));
cbd.BindFlags = D3D11_BIND_CONSTANT_BUFFER;
cbd.ByteWidth = sizeof(cbMatrix);
cbd.Usage = D3D11_USAGE_DEFAULT;

D3D11_SUBRESOURCE_DATA cbdInitData;
ZeroMemory(&cbdInitData, sizeof(D3D11_SUBRESOURCE_DATA));
cbdInitData.pSysMem = &cbMatrix;

mD3DDevice->CreateBuffer(&cbd, &cbdInitData, &mD3DCBuffer);
mD3DImmediateContext->VSSetConstantBuffers(0, 1, &mD3DCBuffer);

When i simply do not include any transformations (output.position = position) in the shader file, everything renders correctly, I see the front face of the cube. Is this all I need to pass constant buffers to my shader and utilize them completely? What am i missing here?

Answer 1

I figured out the answer to my own question, I needed to transpose the matrices by calling D3DXMatrixTranspose() before sending them to the shader.