My goal is to render 3D shapes on top of an image created from .png file. I will render only on certain parts of this image and I would like to keep those parts as separate NDC coordinate systems.
Therefore, I created three tiles:
full screen tile to render background 2D image
smaller tile in the left side of the image area
another smaller tile in the right side of the image area
Everything is working as expected (coordinate systems, positioning, rendering) except the tile background color which apparently ignores the alpha value.
My tiles and functions set background color to {value,value,value,0.0f}. I expected that to make the tile background transparent. Instead, tile background color corresponds to the one made of color values and it covers my image.
How can I set tile background to be transparent and not overlay on top of my full screen background image?
I plan on rendering lines, linestrips and triangles (3D) in separate coordinate systems (two tiles each with range -1,1) using dwRenderEngine_render().
(Image is rendered using render image 2D)
For creating tiles I am using:
dwRenderEngine_initTileState(), then setting params and then _addTile().