Rendering a image with some transparency has removed all black pixels and makes full texture transparent

Question

I am writing a program where with Directx11 I am rendering a texture to a flat rectangle something along the line a of 2D engine. Now parts of this image need to be transparent, to this effect I looked into alpha blending and it seemed to work until i changed textures and realized that it had removed all black pixels and made the whole image transparent not just those pixels that are blank. So how in Directx11 do you have it so that you preserve the transparency of the original image. I am using a ShaderResourceView that is a loaded png for the texture

**//Setup Blend State
D3D11_BLEND_DESC BlendStateDescription;
ZeroMemory(&BlendStateDescription, sizeof(D3D11_BLEND_DESC));


BlendStateDescription.RenderTarget[0].BlendEnable = TRUE;
BlendStateDescription.RenderTarget[0].RenderTargetWriteMask = D3D11_COLOR_WRITE_ENABLE_ALL;
BlendStateDescription.RenderTarget[0].SrcBlend = D3D11_BLEND_SRC_ALPHA;


BlendStateDescription.RenderTarget[0].DestBlend = D3D11_BLEND_INV_SRC1_COLOR;
BlendStateDescription.RenderTarget[0].SrcBlendAlpha = D3D11_BLEND_ONE;
BlendStateDescription.RenderTarget[0].DestBlendAlpha = D3D11_BLEND_ONE;
BlendStateDescription.RenderTarget[0].BlendOp = D3D11_BLEND_OP_ADD;
BlendStateDescription.RenderTarget[0].BlendOpAlpha = D3D11_BLEND_OP_ADD;


dev->CreateBlendState(&BlendStateDescription, &blend);
float blendFactor[] = { 0, 0, 0, 0 };
UINT sampleMask = 0xffffffff;

devcon->OMSetBlendState(blend, blendFactor, sampleMask);**

Answer 1

Your blend state isn't set up to be standard alpha-blending. The general blend state specifies dest.rgb = src.rgb * [SrcBlend] [Op] dest.rgb * [DestBlend], and likewise for the separately blended alpha channel. For standard alpha-blending, you should use:

SrcBlend = D3D11_BLEND_SRC_ALPHA
DestBlend = D3D11_BLEND_INV_SRC_ALPHA
BendOp = D3D11_BLEND_OP_ADD
// dest.rgb = src.rgb * src.a + dest.rgb * (1 - src.a) ==> standard alpha blended color

SrcBlendAlpha = D3D11_BLEND_INV_DEST_ALPHA
DestBlendAlpha = D3D11_BLEND_ONE
BendOp = D3D11_BLEND_OP_ADD
// dest.a = src.a * (1 - dest.a) + dest.a
//       == src.a + dest.a - src.a * dest.a
//       == 1 - (1 - src.a) * (1 - dest.a) ==> preserves alpha to target (optional)