Hallo!
I have again a basic alpha blending problem, where I don't find a solution:
For example I have two images (A + B), which are overlapping at a small
part (C):
----------------
| image A |
| |
| |------------------
| | C | |
-----------|---- |
| |
| image B |
-------------------
Now I want that image A and image B looks normal (unchanged) and in the
overlapping part the two images are added so that one sees both - and
all this with openGL commands (not pix_add or similar, because I have
lots of such regions).
OK, I gave all images an alpha value of 0.5, but then the whole image
losses brightness.
So my question: is there a way to get this alpha blending and without a
loss of brightness in the images ? or can I "renormalize" this effect
somehow (re-increase the brightness) ?
(see attached patch where I illustruted this problem with 2 colored
rectangles)
Thanks for any hint,
LG
Georg
#N canvas 545 0 684 281 10;
#X obj 27 140 gemwin;
#X msg 44 71 create \, 1;
#X msg 47 102 destroy;
#X obj 161 205 rectangle 2 1;
#X obj 162 71 gemhead;
#X obj 163 107 colorRGB 1 0 0 0.5;
#X floatatom 267 61 5 0 0 0 - - -;
#X obj 466 204 rectangle 2 1;
#X obj 467 74 gemhead;
#X floatatom 574 70 5 0 0 0 - - -;
#X obj 163 178 alpha;
#X obj 467 176 alpha;
#X obj 161 141 translateXYZ -1 0 0;
#X obj 469 136 translateXYZ 1 0.2 0;
#X obj 469 104 colorRGB 0 1 0 0.5;
#X text 260 26 when you change these alpha values here \, also the
colors of the non-overlapping region change:;
#X connect 1 0 0 0;
#X connect 2 0 0 0;
#X connect 4 0 5 0;
#X connect 5 0 12 0;
#X connect 6 0 5 4;
#X connect 8 0 14 0;
#X connect 9 0 14 4;
#X connect 10 0 3 0;
#X connect 11 0 7 0;
#X connect 12 0 10 0;
#X connect 13 0 11 0;
#X connect 14 0 13 0;
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