Bug 320651

These bugs becomes because of "Wash" painting mode. 
"Build-Up" painting mode has no artifacts. 
Screen by DmitryK: http://i.imgur.com/m5IgS8j.png

Hi mifth, thanks for the report.

I can confirm the behavior on number 1), the brush seems to have a different spacing exiting the stroke as the one set. On the other hand, with some effort the dabs can be done also in the entry stroke. Lowering the spacing makes the defect disappear. It probably is a bug as the difference between the entry stroke and the exit one are quite different.

The second one I can fully confirm as suggested. Also, turning on rotation for clip brush produces a deep shadow around the brush tip.

To get the artifacts on color brush tip set a low saturated color as the example provided in the bug report.

THE THIRD BUG IS HERE:

Another issue is found with Build-Up Mode. If i draw with a smooth brush i get artifacts if layer has alpha>0.

EXPLANATION:
http://i.imgur.com/MFHKGaF.png
http://i.imgur.com/KvhsspK.png
Source file for testing: https://dl.dropboxusercontent.com/u/26887202/blender/build-up_issue.psd

Confirmed since Vanyossie confirmed the bug.

Git commit 166ea4cb56baf4a5068912dc1567963dcab7a4cb by Dmitry Kazakov.
Committed on 29/06/2013 at 08:10.
Pushed by dkazakov into branch 'krita-testing-kazakov'.

Fixed a pressure bug in Wash-mode of painting

When the pressure drops, the opacity drops as well. In this moment, to
avoid the artifacts while painting the ALPHA_DARKEN op should work in a
reversed way. That is the contents of the layer should be painted on the
top of the brush dab. To allow this, we now keep the average value of the
opacity of several last dabs to be able to reverse the composite op.

This is tested to work best with spacings 0.1-0.2. With other spacing
values, probably, one needs to correct exponent value in
ParameterInfo::updateOpacityAndAverage().

M  +52   -6    krita/benchmarks/kis_composition_benchmark.cpp
M  +6    -1    krita/benchmarks/kis_composition_benchmark.h
M  +6    -2    krita/image/kis_painter.cc
M  +7    -0    krita/image/kis_painter.h
M  +2    -2    krita/plugins/paintops/libpaintop/kis_pressure_flow_opacity_option.cpp
M  +1    -1    krita/plugins/paintops/libpaintop/kis_pressure_opacity_option.cpp
M  +13   -0    libs/pigment/KoCompositeOp.cpp
M  +12   -1    libs/pigment/KoCompositeOp.h
M  +18   -3    libs/pigment/compositeops/KoCompositeOpAlphaDarken.h
M  +71   -24   libs/pigment/compositeops/KoOptimizedCompositeOpAlphaDarken32.h
M  +13   -7    libs/pigment/compositeops/KoOptimizedCompositeOpOver32.h
M  +7    -5    libs/pigment/compositeops/KoStreamedMath.h

http://commits.kde.org/calligra/166ea4cb56baf4a5068912dc1567963dcab7a4cb

Git commit b9d749eb4e7c6bbc00332c9d1c090c9a2293af74 by Dmitry Kazakov.
Committed on 16/07/2013 at 10:43.
Pushed by dkazakov into branch 'master'.

A significant refactoring in the Predefined Brush engine

This patch ports the predefined brush engine to the new capabilities
of Qt. It removes a huge chunk of hand-written code. Here is a short list
of changes:

1) All the operations are now performed on non-premultiplied RGB values.
   The use of premultiplication resulted in instability of the color,
   which caused artifacts on scaling and rotation of the brushes.

2) Trilinear filtering of the brushes is now substituted with simple
   bilinear filtering from the nearest pyramid level.

   It turned out that trilinear filtering not only impacted the
   performance, but also introduced heavy aliasing artifacts on specific
   zoom levels.

3) After the patch the speed of the dab generation raised 3-5 times. Here
   are the values for 512px brush:
   Before patch:
      Scaling:   34 ms
      Rotation:  19 ms
   After patch:
      Scaling:   6 ms
      Rotation:  9 ms
Related: bug 320368, bug 319944, bug 300665
CCMAIL:kimageshop@kde.org

M  +1    -2    krita/plugins/paintops/libbrush/CMakeLists.txt
M  +0    -1    krita/plugins/paintops/libbrush/kis_abr_brush.cpp
M  +1    -1    krita/plugins/paintops/libbrush/kis_auto_brush.cpp
M  +70   -778  krita/plugins/paintops/libbrush/kis_brush.cpp
M  +3    -26   krita/plugins/paintops/libbrush/kis_brush.h
M  +2    -3    krita/plugins/paintops/libbrush/kis_gbr_brush.cpp
D  +0    -135  krita/plugins/paintops/libbrush/kis_qimage_mask.cpp
D  +0    -138  krita/plugins/paintops/libbrush/kis_qimage_mask.h
A  +196  -0    krita/plugins/paintops/libbrush/kis_qimage_pyramid.cpp     [License: GPL (v2+)]
A  +52   -0    krita/plugins/paintops/libbrush/kis_qimage_pyramid.h     [License: GPL (v2+)]
D  +0    -64   krita/plugins/paintops/libbrush/kis_scaled_brush.cpp
D  +0    -62   krita/plugins/paintops/libbrush/kis_scaled_brush.h
A  +-    --    krita/plugins/paintops/libbrush/tests/data/brush_masks/_brush_0_sc_0.871853_rot_3.55731_sub_0.137199.png
A  +-    --    krita/plugins/paintops/libbrush/tests/data/brush_masks/_brush_1_sc_0.861342_rot_3.45867_sub_0.20933.png
A  +-    --    krita/plugins/paintops/libbrush/tests/data/brush_masks/_brush_2_sc_1.80941_rot_4.97706_sub_0.113862.png
A  +-    --    krita/plugins/paintops/libbrush/tests/data/brush_masks/_brush_3_sc_0.46124_rot_4.18791_sub_0.167627.png
A  +-    --    krita/plugins/paintops/libbrush/tests/data/brush_masks/_brush_4_sc_0.963137_rot_2.82314_sub_0.444059.png
A  +-    --    krita/plugins/paintops/libbrush/tests/data/brush_masks/_brush_5_sc_0.592981_rot_0.439579_sub_0.45074.png
A  +-    --    krita/plugins/paintops/libbrush/tests/data/brush_masks/_brush_6_sc_1.86775_rot_3.12606_sub_0.365777.png
A  +-    --    krita/plugins/paintops/libbrush/tests/data/brush_masks/_brush_7_sc_1.13937_rot_3.47854_sub_0.458733.png
A  +-    --    krita/plugins/paintops/libbrush/tests/data/brush_masks/_brush_8_sc_1.53198_rot_3.68719_sub_0.410264.png
A  +-    --    krita/plugins/paintops/libbrush/tests/data/brush_masks/_brush_9_sc_1.46566_rot_2.88023_sub_0.474873.png
M  +-    --    krita/plugins/paintops/libbrush/tests/data/result_autobrush_3.png
M  +-    --    krita/plugins/paintops/libbrush/tests/data/result_autobrush_4.png
A  +-    --    krita/plugins/paintops/libbrush/tests/data/testing_brush_512_bars.gbr
M  +24   -28   krita/plugins/paintops/libbrush/tests/kis_auto_brush_test.cpp
M  +91   -17   krita/plugins/paintops/libbrush/tests/kis_brush_test.cpp
M  +7    -2    krita/plugins/paintops/libbrush/tests/kis_brush_test.h
M  +5    -4    krita/plugins/paintops/libbrush/tests/kis_imagepipe_brush_test.cpp

http://commits.kde.org/calligra/b9d749eb4e7c6bbc00332c9d1c090c9a2293af74

Hi Dmitry!
It seems you did not push the fix with alpha multiply. There is no the fix in latest update.
http://i.imgur.com/UUAbx4P.png 
I'm on master.
But your fix was about 2 days ago. Possibly something was merged incorrectly? 

Thanks.

But your fix was in master about 2 days ago*

Yes, the fix was reverted due to the bug 321935 introduced by it. Now the patch is store in krita-testing-kazakov until I fix this regression.

Git commit c42aa8266818d05a6af24c7194d8e4bf53172e3f by Dmitry Kazakov.
Committed on 25/09/2013 at 19:32.
Pushed by dkazakov into branch 'krita-testing-kazakov'.

The copy-constructor should be implemented for structures having pointers
Related: bug 321935

M  +25   -0    libs/pigment/KoCompositeOp.cpp
M  +5    -6    libs/pigment/KoCompositeOp.h

http://commits.kde.org/calligra/c42aa8266818d05a6af24c7194d8e4bf53172e3f