Vertices not rendering - DirectX

Question

I am learning DirectX and trying to make sure I understand what the functions are doing before I move on to creating an index buffer (which is why I am using repetitive Vertices instead of specific indices). I am trying to render a square but I only have one triangle displaying. I am sure that it is my misunderstanding of the winding order or offsetting the values when passing to the shader but I cant find the issue. Below is the current relevant code and the result at runtime.

void RenderFrame(void) {

// Clear BackBuffer to a color
devContext->ClearRenderTargetView(backbuffer, D3DXCOLOR(0.0f, 0.2f, 0.4f, 1.0f));

// select which vertex buffer to display
UINT stride = sizeof(Vertex);
UINT offset = 0;
devContext->IASetVertexBuffers(0, 1, &pVBuffer, &stride, &offset);

// select which primtive type we are using
devContext->IASetPrimitiveTopology(D3D10_PRIMITIVE_TOPOLOGY_TRIANGLELST);

// draw the vertex buffer to the back buffer
devContext->Draw(6, 0);

// swap buffers
swapchain->Present(0, 0);
}

void ParseGraphics() {

// Create a triangle with the Vertex Struct
Vertex square[] =
{
    { 0.2f, 0.5f, 0.5f, D3DXCOLOR(0.0f, 0.0f, 1.0f, 1.0f) }, //top-right
    { 0.2f, -0.5f, 0.5f, D3DXCOLOR(0.0f, 0.0f, 0.0f, 1.0f) }, //bottom-right
    { -0.2f, -0.5f, 0.5f, D3DXCOLOR(1.0f, 0.0f, 0.0f, 1.0f) }, //bottom-left
    { 0.2f, -0.5f, 0.5f, D3DXCOLOR(0.0f, 0.0f, 0.0f, 1.0f) }, //bottom-right
    { -0.2f, -0.5f, 0.5f, D3DXCOLOR(1.0f, 0.0f, 0.0f, 1.0f) }, //bottom-left
    { -0.2f, 0.5f, 0.5f, D3DXCOLOR(0.0f, 1.0f, 0.0f, 1.0f) }, //top-left


};

// Create Vertex Buffer
D3D11_BUFFER_DESC bd;
ZeroMemory(&bd, sizeof(bd));

bd.Usage = D3D11_USAGE_DYNAMIC;
bd.ByteWidth = sizeof(Vertex) * 6;
bd.BindFlags = D3D11_BIND_VERTEX_BUFFER;
bd.CPUAccessFlags = D3D11_CPU_ACCESS_WRITE;

dev->CreateBuffer(&bd, NULL, &pVBuffer);

// copy vertices into buffer
D3D11_MAPPED_SUBRESOURCE msr;
devContext->Map(pVBuffer, NULL, D3D11_MAP_WRITE_DISCARD, NULL, &msr);
memcpy(msr.pData, square, sizeof(square));
devContext->Unmap(pVBuffer, NULL);

}

void BuildPipeline() {
// Load and Compile Shaders
ID3D10Blob *VS, *PS;
D3DX11CompileFromFile(L"shaders.shader", 0, 0, "VShader", "vs_5_0", 0, 0, 0, &VS, 0, 0);
D3DX11CompileFromFile(L"shaders.shader", 0, 0, "PShader", "ps_5_0", 0, 0, 0, &PS, 0, 0);

// Create shaders from the data in the Blobs Buffer
dev->CreateVertexShader(VS->GetBufferPointer(), VS->GetBufferSize(), NULL, &pVS);
dev->CreatePixelShader(PS->GetBufferPointer(), PS->GetBufferSize(), NULL, &pPS);

// Apply Shaders to the device context
devContext->VSSetShader(pVS, 0, 0);
devContext->PSSetShader(pPS, 0, 0);

// Define the layout of the input given to the shaders
D3D11_INPUT_ELEMENT_DESC ied[] =
{
    {"POSITION", 0, DXGI_FORMAT_R32G32B32A32_FLOAT, 0, 0, D3D11_INPUT_PER_VERTEX_DATA, 0},
    {"COLOR", 0, DXGI_FORMAT_R32G32B32A32_FLOAT, 0, 24, D3D11_INPUT_PER_VERTEX_DATA, 0},

};

dev->CreateInputLayout(ied, 2, VS->GetBufferPointer(), VS->GetBufferSize(), &pLayout);
devContext->IASetInputLayout(pLayout);

}

Answer 1

{"POSITION", 0, DXGI_FORMAT_R32G32B32A32_FLOAT, 0, 0, D3D11_INPUT_PER_VERTEX_DATA, 0}

should be DXGI_FORMAT_R32G32B32_FLOAT as the position has only three members. The AlignedByteOffset can be set to 12 (4x3).

Answer 2

For the topology, you specify D3D10_PRIMITIVE_TOPOLOGY_TRIANGLESTRIP, so the vertex data is expected to form a triangle strip. However, the data you provide specifies two separate triangles (i.e. a triangle list), so you should probably use

devContext->IASetPrimitiveTopology(D3D10_PRIMITIVE_TOPOLOGY_TRIANGLELIST); 

The essential mistake seems to be in the Draw() call: you specify that you want to draw a total of 3 vertices, while you actually want to draw all 6 vertices from your buffer. I.e.

devContext->Draw(6, 0);

The byte offset of your Color element description is wrong, too. The position takes 3 single precision floats (3*4 = 12 bytes), and is directly followed by the color data.

{"COLOR", 0, DXGI_FORMAT_R32G32B32A32_FLOAT, 0, 12, D3D11_INPUT_PER_VERTEX_DATA, 0},