If you want to produce connected lines then each invocation of the GS has to know where the previous invocation put its last point, otherwise it won't know where to start its own line. So you sould use a line strip as your input primitive to the pipeline, then the GS would know both the current and the next point's location, and you could act accordingly when placing the output vertices. However, this would require double computation in the GS, which probably isn't that efficient - but if efficiency isn't what you are after, then that might work for you.
Did i understand it right that i just shall add another point to the location where the second line is draw? so its just a "faked" connection because there are two points on the exakt same location?
Sorry if this question is dumb, but what is my input primitive ? IASetPrimitiveTopology this one? if you mean that - if i use something beside the POINTLIST i get the error
So you sould use a line strip as your input primitive to the pipeline
D3D11 ERROR: ID3D11DeviceContext::DrawIndexed: The declared input primitive type in the current Geometry Shader does not match the current input topology. [ EXECUTION ERROR #360: DEVICE_DRAW_GS_INPUT_PRIMITIVE_MISMATCH]