Can we draw alpha image in viewport

Dunhou

Hey,

I want to draw images with alpha in viewport, but what I got is a image with black bg, I already test DrawTexture flag DRAW_ALPHA_NORMAL_FROM_IMAGE and DRAW_ALPHA_FROM_IMAGE, they will not work.

Can I draw bitmaps with alpha in viewport, like the little icon under the mouse?

Cheers~
DunHou

ferdinand

Hey @Dunhou,

Can you please share code and possibly a bug report? Alphas with DrawTexture have a troubled history but when I tried in the py-ocio_node_2025 example right now, it works for me.

Cheers,
Ferdinand

Result

We draw the little cube icon with alphas next to the existing drawing examples.

Code

I just added the highlighted code in the py-ocio_node_2025 example.

                # Draw the texture and a label for the flag below it.
                bd.DrawTexture(self._bitmap, points, texColors, texNormals, texUVs, 4, 
                               c4d.DRAW_ALPHA_NORMAL, flags)

                # --- new code: start ---
                
                icon: c4d.bitmaps.BaseBitmap | None = c4d.bitmaps.InitResourceBitmap(c4d.Ocube)
                if icon:
                    points: list[c4d.Vector] = [
                        c4d.Vector(xb, ya, 0),
                        c4d.Vector(xb + 20, ya, 0),
                        c4d.Vector(xb + 20, ya + 20, 0),
                        c4d.Vector(xb, ya + 20, 0)
                    ]

                    bd.DrawTexture(icon, points, texColors, texNormals, texUVs, 4, 
                                   c4d.DRAW_ALPHA_NORMAL, flags)

                # --- new code: end ---

                bd.DrawHUDText(xa, yb, "USE_PROFILE_COLOR" if isProfile else "NONE")

edit: I made my changes part of the official code example, as I thought it does not hurt to show that there too.

Dunhou

Sorry for my stupid question @ferdinand , I should use c4d.DRAW_ALPHA_NORMAL but not c4d.DRAW_ALPHA_FROM_IMAGE.

Shame on me

Cheers~
DunHou

ferdinand

I do not think that DRAW_ALPHA_FROM_IMAGE should not work. I just picked DRAW_ALPHA_NORMAL because it is the "most default one" out of the DRAW_ALPHA flags. I will have a look later. But you can for now probably just use DRAW_ALPHA_NORMAL.