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Using the Input-Assembler Stage without Buffers

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Creating and binding buffers is not necessary if your shaders don't require buffers. This section contains an example of simple vertex and pixel shaders that draw a single triangle.

Vertex Shader

For example, you could declare a vertex shader that creates its own vertices.

struct VSIn
{
    uint vertexId : SV_VertexID;
};

struct VSOut
{
    float4 pos : SV_Position;
    float4 color : color;
};

VSOut VSmain(VSIn input)
{
    VSOut output;
    
    if (input.vertexId == 0)
        output.pos = float4(0.0, 0.5, 0.5, 1.0);
    else if (input.vertexId == 2)
        output.pos = float4(0.5, -0.5, 0.5, 1.0);
    else if (input.vertexId == 1)
        output.pos = float4(-0.5, -0.5, 0.5, 1.0);
    
    output.color = clamp(output.pos, 0, 1);
    
    return output;
}

Pixel Shader

// NoBuffer.fx
// Copyright (c) 2004 Microsoft Corporation. All rights reserved.
//

struct PSIn
{
    float4 pos : SV_Position;
    linear float4 color : color;
};

struct PSOut
{
    float4 color : SV_Target;
};


PSOut PSmain(PSIn input)
{
    PSOut output;
    
    output.color = input.color;
    
    return output;
}

Technique

A technique is a collection of rendering passes (there must be at least one pass).

VertexShader vsCompiled = CompileShader( vs_4_0, VSmain() );

technique10 t0
{
    pass p0
    {
        SetVertexShader( vsCompiled );
        SetGeometryShader( NULL );
        SetPixelShader( CompileShader( ps_4_0, PSmain() ));
    }  
}

Application Code

m_pD3D11Device->IASetInputLayout( NULL );

m_pD3D11Device->IASetPrimitiveTopology( D3D_PRIMITIVE_TOPOLOGY_TRIANGLELIST );
    
ID3DX11EffectTechnique * pTech = NULL;
pTech = m_pEffect->GetTechniqueByIndex(0);
pTech->GetPassByIndex(iPass)->Apply(0);

m_pD3D11Device->Draw( 3, 0 );

Getting Started with the Input-Assembler Stage