On Tue, Dec 13, 2005 at 10:11:51PM +0530, Sourath Roy wrote: > Hi, > I am using DirectFB-0.9.22 on Linux nVidia(NV32) Framebuffer support(kernel > 2.6.13). > On a surface with > PorterDuff rule set as DSPD_SRC, > DrawingFlags set to DSDRAW_BLEND, and > pixelformat set to DSPF_ARGB > > I don't see any BLEND effect with varying alpha component of color.
You're using DSPD_SRC so the result is correct. > For > example if I do a SetColor with red = 0xff and alpha = 1, and do a > FillRectangle I see a solid red rectangle. The effect is same as alpha = > 0xff. > I observe a change in behavior when I OR the DrawingFlags with > DSDRAW_SRC_PREMULTIPLY. Then I can see the blend. Actually you only see the effect of multiplying the source color with source alpha but you still don't see any blend with the destination. > Shouldn't the alpha component change impact the drawing without > DSDRAW_SRC_PREMULTIPLY flag? Because DSDRAW_SRC_PREMULTIPLY forces a change > in red, green, blue components and thus the effect is seen. Changing alpha > component alone should make a visible difference, isn't it? Not with DSPD_SRC. Read the Porter/Duff descriptions in directfb.h. -- Ville Syrjälä [EMAIL PROTECTED] http://www.sci.fi/~syrjala/ _______________________________________________ directfb-users mailing list [email protected] http://mail.directfb.org/cgi-bin/mailman/listinfo/directfb-users
