Rework Sobel a little bit again making it work as the old one:
1. desaturate input texture
2. calculate horizontal convolution for x gradient and vertical
convolution for y gradient at the same time (halves the number of
needed texture lookups)
3. store results in a single texture (red and green channel)
4. calculate remaining convolution (same as above switching vertical and
horizontal)
5. calculate length of gradient using red and green as x and y
components.
Optimize wherever possible, store kernels as constants in the shaders,
remove unneeded uniforms. Restore invert property carefully avoiding
using IF.
Still not sure if "full color" convolution will be needed, glfiltersobel
is to be intended as a demo filter and xray, the only effect which uses
sobel only needs edge intensity. Dropping it for now.
Reimplement sobel in a multipass fully separated convolution:
- calculate x gradient map convolving first horizontally with blurring
kernel and then vertically with differentiating kernel
- calculate y gradient map convolving first vertically with blurring
kernel and then horizonally with differentiating kernel
- calculate length of the gradient vector
Particular care was needed with normalization of the blurring kernel and
with grey level offset of the differentiating one to prevent overflow of
rgb values from the [0.0,1.0] range in intermediate passes.
Now works on i915.
Thanks to Eric Anholt I've finally understood (at least I hope) how to
count texture indirections and save up some. Texture sampling dependent
on the result of some math counts as an indirection phase. Grouped
texture lookups with no math involved count as a single indirection.
Math on the coordinates count as indirection.
So the best thing is to group all the math involving coordinates and
then do all the lookups.
This saves enough indirections to make glfilterblur and glow effect
work, albeit a bit slowly, on i915.
Apparently assigning gl_TexCoord to a temp count as an indirection.
Using it directly avoids it and limits indirections to four not
exceeding i915 limit. Now xpro effect works on i915.
Get rid of polar coordinates in the twirl effect. The same can be done
using a rotation matrix, saving alu instructions and, most of all,
avoiding the use of the evil atan() function (which uses IF operators).
Calculate rotation angle in a saner, understandable way.
Works on i915! (Hope it still works elsewhere too as I'm not able to
test at the moment)
Get rid of polar coordinates in the tunnel effect as the same can easily
be done just clamping the radius and multiplying.
Remove the evil atan() call that uses branching and a lot of unneeded alu
instructions. Now works on i915!
Generate a normalized gaussian kernel with given size and standard
deviation on the fly.
Remove "norm_const" uniform from convolution shaders and provide a
normalized kernel instead. Remove norm_offset uniform as it was always
zero, will reintroduce it if really needed in the future. Thanks to Eric
Anholt for suggesting it.
Save some ALU instruction calculating directly the coordinate for
texture lookup instead of summing an offset.
Still exceed maximum indirect texture lookups on i915, the only solution
I see is using a 3x3 kernel.
Reduce the number of register calculating texture lookup offset on the
fly. It was just a simple sequence, no need to store it in a array.
Fixes maximum number of registers exceeded error with i915. Still
exceed maximum indirect texture lookups and maximum ALU instructions.
Maybe we should gave up some blur goodness and use lightly more little
kernels.
Apparently saving up some texture lookup for zero kernel elements is
definitely not worth the use of branching. This way convolution
fragment programs also work where IF operator is not supported (tested
on i915 and nouveau). See also discussion on bug #615696.
Thanks to Eric Anholt for spotting this.
Fix some crazy formatting caused by gst-indent previous runs and disable
the script for this file. The best would be to move shaders into
separate files and load them at runtime or hardcode them at compile
time.
For now only identity, mirror and squeeze effects are available.
Maybe some factorization is needed about compilation shader
before to put the other effects since only a copy/past is needed,
at least until effect number 9: heat.
The effects from 10:sepia to 15:glow require more work.
The background image needs to be scaled to fit current texture size.
Previously this was done by gdk_pixbuf_scale_simple but that's been
removed.
Create a texture from the background pixbuf with correct dimensions and
use interpolation shader to scale it to the right size. Interpolation
fragment shader doesn't have too much sense if all the textures don't
have the same size so this seemed the most natural place to do the
scaling. It could probably be done with some custom texture mapping
outside the shader but it involved more code.
Fixes bug #599883.
This reverts commit 96e4ab18c2cf9876f6c031b9aba6282d0bd45a93.
You should have asked first. And you would have been told "no",
because it causes people on development branches to do a huge
amount of extra work.
