Draw/Remove geometrical shapes on render target using DirectX 11 - directx

Question

I am trying to draw/remove geometrical shapes on render target which displays a image.
During each frame render, a new image is rendered to the render target by updating the resource via texture mapping which works perfectly as expected.
Now, I'm trying to draw a new geometrical shape filled with a solid color on top of the render target, which is only done during the rendering of every 10th frame.
However currently stuck as to how i should approach this.
I'm using DirectX 11 on windows 7 PC with C# (slimDx or sharpDx for DirectX).
Any suggestion would be great.
Thanks.
Code:
During rendring loop i added the code below to draw the overlay which is a triangle in my case.
var device = this.Device;
var context = device.ImmediateContext;
var effectsFileResource = Properties.Resources.ShapeEffect;
ShaderBytecode shaderByteCode = ShaderBytecode.Compile(effectsFileResource, "fx_5_0", ShaderFlags.EnableStrictness | ShaderFlags.Debug, EffectFlags.None);
var effect = new Effect(device, shaderByteCode);
// create triangle vertex data, making sure to rewind the stream afterward
var verticesTriangle = new DataStream(VertexPositionColor.SizeInBytes * 3, true, true);
verticesTriangle.Write(new VertexPositionColor(new Vector3(0.0f, 0.5f, 0.5f), new Color4(1.0f, 0.0f, 0.0f, 1.0f)));
verticesTriangle.Write(new VertexPositionColor(new Vector3(0.5f, -0.5f, 0.5f), new Color4(0.0f, 1.0f, 0.0f, 1.0f)));
verticesTriangle.Write(new VertexPositionColor(new Vector3(-0.5f, -0.5f, 0.5f), new Color4(0.0f, 0.0f, 1.0f, 1.0f)));
verticesTriangle.Position = 0;
// create the triangle vertex layout and buffer
var layoutColor = new InputLayout(device, effect.GetTechniqueByName("Color").GetPassByIndex(0).Description.Signature, VertexPositionColor.inputElements);
var vertexBufferColor = new SharpDX.Direct3D11.Buffer(device, verticesTriangle, (int)verticesTriangle.Length, ResourceUsage.Default, BindFlags.VertexBuffer, CpuAccessFlags.None, ResourceOptionFlags.None, 0);
verticesTriangle.Close();
var srv = new ShaderResourceView(device, this.RenderTarget);
effect.GetVariableByName("g_Overlay").AsShaderResource().SetResource(srv);
// Think of the shared textureD3D10 as an overlay.
// The overlay needs to show the 2d content but let the underlying triangle (or whatever)
// show thru, which is accomplished by blending.
var bsd = new BlendStateDescription();
bsd.RenderTarget[0].IsBlendEnabled = true;
bsd.RenderTarget[0].SourceBlend = BlendOption.SourceColor;
bsd.RenderTarget[0].DestinationBlend = BlendOption.BlendFactor;
bsd.RenderTarget[0].BlendOperation = BlendOperation.Add;
bsd.RenderTarget[0].SourceAlphaBlend = BlendOption.One;
bsd.RenderTarget[0].DestinationAlphaBlend = BlendOption.Zero;
bsd.RenderTarget[0].AlphaBlendOperation = BlendOperation.Add;
bsd.RenderTarget[0].RenderTargetWriteMask = ColorWriteMaskFlags.All;
var blendStateTransparent = new BlendState(device, bsd);
context.InputAssembler.InputLayout = layoutColor;
context.InputAssembler.PrimitiveTopology = PrimitiveTopology.TriangleStrip;
context.InputAssembler.SetVertexBuffers(0, new VertexBufferBinding(vertexBufferColor, VertexPositionColor.SizeInBytes, 0));
context.OutputMerger.BlendState = blendStateTransparent;
var currentTechnique = effect.GetTechniqueByName("Color");
for (var pass = 0; pass < currentTechnique.Description.PassCount; ++pass)
{
using (var effectPass = currentTechnique.GetPassByIndex(pass))
{
System.Diagnostics.Debug.Assert(effectPass.IsValid, "Invalid EffectPass");
effectPass.Apply(context);
}
context.Draw(3, 0);
};
srv.Dispose();
Also below is the shader file for the effect:
Texture2D g_Overlay;
SamplerState g_samLinear
{
Filter = MIN_MAG_MIP_LINEAR;
AddressU = CLAMP;
AddressV = CLAMP;
};
// ------------------------------------------------------
// A shader that accepts Position and Color
// ------------------------------------------------------
struct ColorVS_IN
{
float4 pos : POSITION;
float4 col : COLOR;
};
struct ColorPS_IN
{
float4 pos : SV_POSITION;
float4 col : COLOR;
};
ColorPS_IN ColorVS(ColorVS_IN input)
{
ColorPS_IN output = (ColorPS_IN)0;
output.pos = input.pos;
output.col = input.col;
return output;
}
float4 ColorPS(ColorPS_IN input) : SV_Target
{
return input.col;
}
// ------------------------------------------------------
// A shader that accepts Position and Texture
// Used as an overlay
// ------------------------------------------------------
struct OverlayVS_IN
{
float4 pos : POSITION;
float2 tex : TEXCOORD0;
};
struct OverlayPS_IN
{
float4 pos : SV_POSITION;
float2 tex : TEXCOORD0;
};
OverlayPS_IN OverlayVS(OverlayVS_IN input)
{
OverlayPS_IN output = (OverlayPS_IN)0;
output.pos = input.pos;
output.tex = input.tex;
return output;
}
float4 OverlayPS(OverlayPS_IN input) : SV_Target
{
float4 color = g_Overlay.Sample(g_samLinear, input.tex);
return color;
}
// ------------------------------------------------------
// Techniques
// ------------------------------------------------------
technique11 Color
{
pass P0
{
SetGeometryShader(0);
SetVertexShader(CompileShader(vs_4_0, ColorVS()));
SetPixelShader(CompileShader(ps_4_0, ColorPS()));
}
}
technique11 Overlay
{
pass P0
{
SetGeometryShader(0);
SetVertexShader(CompileShader(vs_4_0, OverlayVS()));
SetPixelShader(CompileShader(ps_4_0, OverlayPS()));
}
}
The above code has been taken from : SharedResources using SharpDX