DrawRectangle.hlsl

matrix orthoProjMatrix;
float4 elementSize;
float4 strokeWidth;

struct VertexShaderInput
{
    float3 position : POSITION0;
    float4 color : COLOR0;
    float2 texCoord : TEXCOORD0;
};

struct PixelShaderInput
{
    float4 position : POSITION0;
    float2 texCoord : TEXCOORD0;
    float4 color : TEXCOORD1;
};

void VertexMain(in VertexShaderInput vsInput, out PixelShaderInput output)
{
    output = (PixelShaderInput)0;

    output.position = mul(float4(vsInput.position, 1), orthoProjMatrix);
    output.texCoord = vsInput.texCoord;
    output.color = vsInput.color;
}

void PixelMain(in PixelShaderInput input, out float4 color : COLOR0)
{
    float texStepSizeX = strokeWidth.x / elementSize.x;
    float texStepSizeY = strokeWidth.x / elementSize.y;
    float2 tex = input.texCoord;

    if(tex.x <= texStepSizeX || tex.y <= texStepSizeY || (1.0f - tex.x) <= texStepSizeX || (1.0f - tex.y) <= texStepSizeY)
        color = input.color;
    else
        color = float4(0, 0, 0, 0);
}