Projecting a targetting ring using direct3d
- by JohnB
I'm trying to draw a "targetting ring" on the ground below a "unit" in a hobby 3d game I'm working on. Basically I want to project a bright red patterned ring onto the ground terrain below the unit.
The only approach I can think of is this -
Draw the world once as normal
Draw
the world a second time but in my
vertex shader I have the world x,y,z
coordinates of the vertex and I can
pass in the coordinates of the
highlighted unit - so I can
calculate what the u,v coordinates
in my project texture should be at
that point in the world for that
vertex.
I'd then use the pixel shader to pick pixels from the target ring texture and blend them into the previously drawn world.
I believe that should be easy, and should work but it involves me drawing the whole visible world twice as it's hard to determine exactly which polygons the targetting ring might fall onto. It seems a big overhead to draw the whole world twice, once for the normal lit textured ground, and then again just to draw the targetting ring.
Is there a better approach that I'm missing?
