Preparation stage ：

The process is as follows ：

  Equipment creation preparation stage ：

ComPtr<ID3DBlob> blob;
	// Create vertex shaders 
	HR(CreateShaderFromFile(L"HLSL\\VS_Hexagon.cso", L"HLSL\\VS_Hexagon.hlsl", "VS", "vs_5_0", blob.ReleaseAndGetAddressOf()));
	m_pDevice->CreateVertexShader(blob->GetBufferPointer(), blob->GetBufferSize(), nullptr, m_pVertexShader.GetAddressOf());
	// Create input layout 
	m_pDevice->CreateInputLayout(VertexPosColor::inputLayout, ARRAYSIZE(VertexPosColor::inputLayout),
		blob->GetBufferPointer(), blob->GetBufferSize(), m_pVertexLayout.GetAddressOf());
	// Create pixel shaders 
	CreateShaderFromFile(L"HLSL\\PS_Hexagon.cso", L"HLSL\\PS_Hexagon.hlsl", "PS", "ps_5_0", blob.ReleaseAndGetAddressOf());
	m_pDevice->CreatePixelShader(blob->GetBufferPointer(), blob->GetBufferSize(), nullptr, m_pPixelShader.GetAddressOf());

    // Describe the vertex description area 
    D3D11_BUFFER_DESC vbd;
	ZeroMemory(&vbd, sizeof(vbd));
	vbd.Usage = D3D11_USAGE_IMMUTABLE;
	vbd.ByteWidth = sizeof vertices;
	vbd.BindFlags = D3D11_BIND_VERTEX_BUFFER;
	vbd.CPUAccessFlags = 0;
	// Vertex buffer data source 
	D3D11_SUBRESOURCE_DATA InitData;
	ZeroMemory(&InitData, sizeof(InitData));
	InitData.pSysMem = vertices;
	m_pDevice->CreateBuffer(&vbd, &InitData, m_pVertexBuffer.GetAddressOf());

Bind device context stage ：

UINT stride = sizeof(VertexPosColor);	//  Number of bytes crossed 
	UINT offset = 0;						//  Starting offset 

	// Bind shader 
	m_pContext->VSSetShader(m_pVertexShader.Get(), nullptr, 0);
	m_pContext->PSSetShader(m_pPixelShader.Get(), nullptr, 0);
	// Set the element type 
	m_pContext->IASetPrimitiveTopology(D3D11_PRIMITIVE_TOPOLOGY_TRIANGLESTRIP);
	// Set the input layout 
	m_pContext->IASetInputLayout(m_pVertexLayout.Get());
	// Bind vertex buffer 
	m_pContext->IASetVertexBuffers(0, 1, m_pVertexBuffer.GetAddressOf(), &stride, &offset);

Element type ：

DirectX11 There are many element types in , The following pictures are easy to understand what the element type is ：

  Whether it is the simplest one-dimensional graph or the more complex multi-dimensional graph , It's all a little 、 Line 、 Surface composition , With primitives , We can pass through the dot 、 Line 、 Triangles and polygons form a multivariate image .

Here are some dx11 Element types and meanings that can be called in ：

The first way to draw （ By element type TRIANGLESTRIP）：

Set the number of drawing vertices ：

Set vertex ：

  Set the element type ：

The second way to draw （ By element type TRIANGLELIST）：

Set the number of drawing vertices ：

Set vertex ： 

Set the element type ：

design sketch ：

  summary ：

When we use TRIANGLESTRIP Element type , We need to 6 Draw a regular hexagon with vertices , While using TRIANGLELIST Element type , You need to draw 12 vertices .

because TRIANGLESTRIP After every three vertices form a triangle , The next triangle can use the first two vertices and then add a vertex to draw another triangle , in other words , We can draw 4 Draw two triangles with two vertices .

and TRIANGLELIST The primitive type needs to create a triangle every three vertices , Even if you draw 4 vertices , You can draw a triangle . Needless to say , because 4 Less than 6, and 2 A triangle needs 6 vertices , Three triangles need 12 vertices ——

remarks ：

Vertices must be created clockwise .

In general , Triangle vertices are created clockwise , It's facing the camera . If the triangle vertices are arranged counterclockwise, it means that the current triangle faces the camera . Triangles facing away from the camera will be eliminated , Do not rasterize . This is called backface culling