I want to use Direct3D 11 to blend several images that from multi-view into one texture, so i do multiple projection at Vertex Shader stage and Geometry Shader stage, one of the projection's result stored in SV_Position, others stored in POSITION0, POSITION1 and so on. These positions would be used to sample the image.
Then at the Pixel shader stage, the value in SV_Position is typical like a (307.5,87.5), because it's in screen space. as the size of render target is 500x500, so the uv for sample is (0.615,0.0.175), it's correct. but value in POSITION0 would be like a (0.1312, 0.370), it's vertical reversed with offset. i have to do (0.5 + x, 0.5 - y). the projection is twisted and just roughly matched.
What do the rasterizer stage do on SV_Position?