Hi Tilman,
Thanks for the feedback. What you mean by the function calculations is it
function evaluation method can you please give more information on it.
About the proposal what advise can you give, is there specific way that
pdfbox expect apart form the gsoc format and is there any sample proposal
that we can get idea about writing proposal.
On Sun, Mar 9, 2014 at 8:42 PM, Tilman Hausherr <thaush...@t-online.de>wrote:
> Hello,
>
> Yes this is an interesting idea. It would save the recalculation of "y1y0
> * (y + j - coords[1])" everytime. (Unless the java compiler detects this
> already)
> But don't expect too much from it - I believe more time is lost in
> function calculation (at least for types 1, 2 and 3 where functions are
> mandatory).
>
> Tilman
>
>
> Am 09.03.2014 15:12, schrieb Thimal Kempitiya:
>
> Thanks Tilman
>>
>> for optimization in speed I think we need to facus on methods which use
>> again and again like getRaster
>>
>> for the axial shading part current implementation in the getRaster method
>> we calculate the x' value for the raster inside the for by for loop
>>
>> for (int j = 0; j < h; j++)
>> {
>> for (int i = 0; i < w; i++)
>> {
>> useBackground = false;
>> double inputValue = x1x0 * (x + i - coords[0]);
>> inputValue += y1y0 * (y + j - coords[1]);
>>
>> but all the time changing happen in the i and j values and they vary from
>> 0<j<h and 0<i<w
>> so the contribution form i and j values can be calculation in separate 2
>> for loops which run from 0 to h and 0 to w and calculate these values
>> separately and put them in 2 arrays and when we need to evaluate we can
>> add
>> to the input value
>>
>> this will reduce the calculations inside the for by for loop and put them
>> inside a 2 for loops this may be speed up the axial shading
>>
>> what you think about it
>>
>>
>> On Fri, Mar 7, 2014 at 11:44 PM, Tilman Hausherr <thaush...@t-online.de
>> >wrote:
>>
>> Am 07.03.2014 15:03, schrieb Thimal Kempitiya:
>>>
>>> Thanks Tilman for the feedback
>>>
>>>> http://www.particleincell.com/blog/2012/quad-interpolation/ seems like
>>>> opposite of what we are going need to check whether its work with this
>>>> by
>>>> implementing it (but can easily implement if we used library with matrix
>>>> manipulations)
>>>>
>>>> This is really up to you :-) Re: the pure math parts, its rather me
>>> who
>>> is learning something.
>>>
>>> Re: library, you can use the java standard library, or any library with
>>> Apache license or compatible license.
>>>
>>>
>>>
>>> can I know more about the optional part in the issue
>>>>
>>>> "Optional:
>>>> Review and optimize the complete shading package; implement cubic spline
>>>> interpolation for type 0 (sampled) functions."
>>>>
>>>> where I can get more information about the cubic spline interpolation
>>>> for
>>>> type 0 (sampled) functions and in what aspects do you expect the
>>>> optimization.
>>>>
>>>> Optimization for speed. Especially the axial shading. It gets slow when
>>> the shaded area is very large.
>>>
>>> The cubic spline interpolation is mentioned in the PDF spec at the type 0
>>> (sampled) functions, it is the part where order = 3. In the PDF spec,
>>> search for it, or for "Additional entries specific to a type 0 function
>>> dictionary". Its really just a "nice to have" and of low priority.
>>> There's
>>> a note from adobe telling that it is not done for printing.
>>>
>>> Tilman
>>>
>>>
>>>
>>>
>>>>
>>>> On Tue, Mar 4, 2014 at 10:13 PM, Tilman Hausherr <thaush...@t-online.de
>>>>
>>>>> wrote:
>>>>>
>>>> Am 04.03.2014 15:19, schrieb Thimal Kempitiya:
>>>>
>>>>> Hi,
>>>>>
>>>>> I checked the code related to the shading and studied the pdf spec
>>>>>> related
>>>>>> to the type 6. As I see it is going same as the type 4
>>>>>> From what I feel this is need to be done correct me if I'm wrong
>>>>>> first need to get the 12 control points and colors related to each
>>>>>> unit
>>>>>> from stream
>>>>>>
>>>>>> Yes
>>>>>>
>>>>>
>>>>> create the 4 cubic Bézier curves which are boundaries of each patch
>>>>> (
>>>>> to
>>>>>
>>>>> find a Bézier curve it need 4 control points, two points are part of
>>>>>> the
>>>>>> curve )
>>>>>>
>>>>>> Yes, although they are not painted as a curve, the curve is part of
>>>>>> a
>>>>>>
>>>>> formula to find out whether a point is inside or outside the patch.
>>>>>
>>>>> given point need to find the point which patch (I think this can be
>>>>>
>>>>> done[1]<http://en.wikipedia.org/wiki/Plane_%28geometry%29>but need
>>>>>>
>>>>>> research on that)
>>>>>> find the color of the point using bi linear interpolation
>>>>>>
>>>>>> Probably. Although I'm not sure if the bilinear interpolation is the
>>>>>>
>>>>> same
>>>>> as used for a rectangle.
>>>>> http://www.particleincell.com/blog/2012/quad-interpolation/
>>>>> I also don't know if the curves needs to be taken into account.
>>>>>
>>>>>
>>>>> This has the same structure as the other shading types but need to
>>>>>
>>>>> structure to keep Bézier curves and patches
>>>>>> and patches are connected as in the type4
>>>>>>
>>>>>> Yes, the data structure is similar. You can use existing code and do
>>>>>>
>>>>> lot
>>>>> of copy & paste there, although there is some rearrangement needed as
>>>>> there
>>>>> are more points.
>>>>>
>>>>>
>>>>>
>>>>> I have to study the type 7 but I think its similar to this
>>>>>
>>>>>> According to the spec, type 6 is a special case of type 7. I cannot
>>>>>>
>>>>> tell
>>>>> whether it is enough to implement type 7 only and derive type 6 from
>>>>> it,
>>>>> i.e. I don't know if the performance would be worse.
>>>>>
>>>>> Tilman
>>>>>
>>>>>
>>>>> please give feedback on my approach
>>>>>
>>>>>> [1]http://en.wikipedia.org/wiki/Plane_%28geometry%29<http
>>>>>> ://en.wikipedia.org/wiki/Plane_%28geometry%29>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Sun, Mar 2, 2014 at 11:18 AM, Thimal Kempitiya <
>>>>>> tkempit...@gmail.com
>>>>>>
>>>>>> wrote:
>>>>>>>
>>>>>>> yeah I'm using trunk code(2.0) and I wanted to render the image
>>>>>> got
>>>>>> it,
>>>>>>
>>>>>> thanks. I'm currently studying the 1 to 5 shading implementations and
>>>>>>> the
>>>>>>> pdf spec related to 6 and 7 type shading and i'll buzz you if i got
>>>>>>> issue.
>>>>>>> Once again thanks for quick reply
>>>>>>>
>>>>>>>
>>>>>>> On Sat, Mar 1, 2014 at 2:38 AM, John Hewson <j...@jahewson.com>
>>>>>>> wrote:
>>>>>>>
>>>>>>> You'll need to use the latest 2.0.0 snapshot jar, which is the
>>>>>>> unstable
>>>>>>>
>>>>>>> version from trunk
>>>>>>>> and the place where new development occurs.
>>>>>>>>
>>>>>>>> -- John
>>>>>>>>
>>>>>>>> On 28 Feb 2014, at 05:04, Thimal Kempitiya <tkempit...@gmail.com>
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> I'm Thimal Kempitiya, third year computer science and engineering
>>>>>>>>> undergraduate at university of moratuwa. I'm interested in the
>>>>>>>>> project
>>>>>>>>>
>>>>>>>>> idea
>>>>>>>>>
>>>>>>>> "implement shading with Coons and tensor-product patch meshes". I
>>>>>>>>
>>>>>>>>> have
>>>>>>>>>
>>>>>>>>> the
>>>>>>>>>
>>>>>>>> basic knowledge about the cubic Bézier curves", , "bilinear
>>>>>>>>
>>>>>>>>> interpolation",
>>>>>>>>>
>>>>>>>> " and "Bernstein polynomials and i think can manage rest of the
>>>>>>>>
>>>>>>>>> mathematics
>>>>>>>>>
>>>>>>>> needed for this project. Also I have the java knowledge to do the
>>>>>>>>
>>>>>>>>> implementation part.
>>>>>>>>>
>>>>>>>>> I clone the PDFBOX repository and checked the code regarding to the
>>>>>>>>>
>>>>>>>>> shading
>>>>>>>>>
>>>>>>>> and I tried some examples in pdfbox cook book.
>>>>>>>>
>>>>>>>>> Also I tried code to work with the type 1 shading type.
>>>>>>>>>
>>>>>>>>> File f=new File("C:\\asy-latticeshading.pdf");
>>>>>>>>> try {
>>>>>>>>> PDDocument doc=PDDocument.load(f);
>>>>>>>>> PDPage p;
>>>>>>>>> p=(PDPage)doc.getDocumentCatalog().
>>>>>>>>> getAllPages().get(0);
>>>>>>>>> PDShadingType1 pdst1=new PDShadingType1(p.
>>>>>>>>> getCOSDictionary());
>>>>>>>>> PDRectangle pdr=p.findCropBox();
>>>>>>>>> PDGraphicsState pdg=new PDGraphicsState(pdr);
>>>>>>>>> Matrix m=pdg.getCurrentTransformationMatrix();
>>>>>>>>> Type1ShadingPaint t1sp=new Type1ShadingPaint(pdst1, m,
>>>>>>>>> (int)p.findCropBox().getHeight());
>>>>>>>>>
>>>>>>>>> But this give me error saying unknown shading type 0
>>>>>>>>> java.io.IOException: Error: Unknown shading type 0
>>>>>>>>>
>>>>>>>>> can you please tell me what I'm doing wrong here and how can i
>>>>>>>>> solve
>>>>>>>>>
>>>>>>>>> this.
>>>>>>>>>
>>>>>>>> --
>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> *Thimal Kempitiya <http://www.facebook.com/thimalk>
>>>>>>>>>
>>>>>>>>> UndergraduateDepartment
>>>>>>>>>
>>>>>>>> of Computer Science and Engineering University of Moratuwa.*
>>>>>>>>
>>>>>>>>>
>>>>>>>>> --
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> *Thimal Kempitiya <http://www.facebook.com/thimalk>
>>>>>>> UndergraduateDepartment of Computer Science and Engineering
>>>>>>> University
>>>>>>> of
>>>>>>> Moratuwa.*
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>
>
--
*Thimal Kempitiya <http://www.facebook.com/thimalk> UndergraduateDepartment
of Computer Science and Engineering University of Moratuwa.*
