I have issue setting up an Openlayers map with vector tiles served from Geoserver. The lines gets screwed up along the edges of the tiles. It looks like the lines are first clipped and then styled instead of the opposite. This makes wide lines look ugly.
Changing the renderBuffer in the OL client doesnt make any difference.
I have similar issues with labels and perhaps the solution is pretty much the same in both cases.
EDIT: The geojson in QGIS shows that there is a buffer around the tiles:
geojson output in QGIS
EDIT 2: I have been doing som more research on the phenomenom and I think both Geoserver and Openlayers are to blame for the artifacts. As seen below, Geoserver does render with a buffer (the pink polygons(1 and 2) contains the black bordered tile extent) but does not include features that lies outside of the tile but inside of the buffer, like the green line(3) in the circle.
That makes the tile rendered with a jack as in the left circle below.
However, even when you have a line in a tile that goes close to the tile border, styled with quite a thick stroke, Openlayers wont render enough of the line outside the tile to make it styled without a jack. Like the right circle below. I have mote obvious examples of that bahviour. This could probably easily be fixed by setting a higher buffer/tolerance value for the tilerendering.
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I am drawing maps in gimp. I have to make text labels with borders around it which are connected with lines, to dots on map.
How hard is it (I never tried scripting in gimp) to write a macro/script which will create/recreate a separate layer and draw lines and borders on it?
I want to speed up my work but I'm afraid that writing a programm will take too much time, coz I'm new to it.
I have been working with OpenGL in iOS, and setting the colors with glColor4f(r,g,b,a) and then drawing my own color on a white UIImageView. I basically have a brush, which is then moved around my user's touch, and then it paints the color onto the canvas. But this color needs to be water paint (like smudged color)
Does anyone understand/knows how to get a water color like this app does, and how the background UIImageView has a texture on it?
https://itunes.apple.com/us/app/hello-watercolor/id539414526?mt=8
or checkout water paint in this. http://www.fiftythree.com/paper
I created a bounty on this as I am really having a hard time to grasp how to derive such smooth flowing colors out of the normal colors. Even if you guys point me in the right direction, or to some sample code on how I can get the effect of water-paint, it would be really helpful ^_^
And as a bonus, it would be also be helpful if you can point out to me how to get canvas on which it is painted on looks realistic, and blended with the paint? Does Blending/GLSL have to do with any of this?
Is there any sample project on this?
If you are still struggling with the basics of getting realistic looking water colors working, you may want to experiment/prototype in photoshop first.
http://www.zoepiel.com/tutorials/watercolor/ shows some very effective tricks for creating watercolor images with simple tools.
The most interesting one is to multiply a group of watercolor layers with a greyscale watercolor paper image. The texture of the paper makes some parts remain white, and other parts saturate with color, just like real watercolor.
Each layer remains 'wet' in the sense that the colors within it blend, but the layers are 'dry' with respect to each other.
She also explains some of her brush and blur settings and shows what they do.
Once you can produce the desired effect in photoshop, you'll have clear specifications of what you want to do and you'll be quite a bit closer to programming it out.
Looking at the examples you posted, it looks like they are using a simple Gaussian Blur with a radius of double your brush size. This may be an incomplete solution, but it's at least the first level.
I am building a 3D image viewer which has Three.JS plane geometries as placeholders with the images as their textures.
Now I want to add a black border around the image. The only way I have found yet to implement this is to add a new black plane geometry behind the image to be displayed. But this required whole-sale changes to my framework which I want to avoid.
WebGL's texture loading function gl.texImage2D has a parameter for border. But I couldn't find this exposed anywhere through Three.js and doubt that it even works the way I think it does.
Is there an easier way to add borders around textures?
You can use a temporary regular 2D canvas to render your image and apply any kind of editing/effects there, like paint borders and such. Then use that canvas image as a texture. Might be a bit of work, but you will gain a lot of flexibility styling your borders and other stuff.
I'm not near my dev machine and won't be for a couple of days, so I can't look up an example of my own. This issue contains some code to get you started: https://github.com/mrdoob/three.js/issues/868
Can anyone share a sample code to draw a non-rectangular part of a picture in delphi canvas?
You're looking for GDI paths. Start here, which explains what paths are in this context, and provides links on the left to explain the functionality available with them.
Google can turn up lots of examples of using paths in Delphi. If you can't find them, post a comment back here and I'll see what I can turn up for you.
Your question is pretty vague. But I suspect what you are looking for is clipping regions. Read up on them. Set the clipping region on the target device to the shape you want, and then draw the image onto the device. Only the part of the image that would be within the clipping region will be drawn.
Canvas.Ellipse(0, 0, 10, 20); // not a rectangle
I use so called runlists for this feature (generalized shapes and blitting them). I've seen them called warplists too. A shape is encoded as a runlist by defining it as a set of horizontal lines, and each line is two integer values (skip n pixels,copy n pixels).
This means you can draw entire lines, leaving you with only "height" draw operations.
So a rectangle is defined (the first "skip" pixels from top level corner to the left corner (xorg,yorg). The rectangle is width_rect wide, and width_pixels goes a line further. width_pixels can be wider than the width of the picture (alignment bytes)
(yorg*width_pixels+xorg , width_rect),
(width_pixels-width_rect , width_rect),
(width_pixels-width_rect , width_rect),
(width_pixels-width_rect , width_rect),
..
..
This way you can make your drawing routines pretty generic, and for simple, regular shapes (rects, circles) it takes only minor math to precalculate these lists. It simplified my shape handling enormously.
However I draw directly to bitmaps, not to canvasses, so I can't help with that part. A primitive that efficiently draws a row, and a way to extract a row from a graphic should be enough.
Imagine you are drawing a map of county borders. You are given a set of polygons, one for each boundary, and you draw each polygon.
In places where two counties share a border you just end up drawing the border twice. In the absence of partial transparency effects, and with a solid pen, this is no problem.
But, on maps, borders of this kind are customarily shown by dash-dotted lines. In this case, situations like the one depicted below can happen:
Notice how the dash pattern, which normally is dash-dot-dot, gets screwed up where the two areas share a border. In this case, it happened to become a longdash-dot pattern, but in general it could do anything from coincidentally looking normal to creating a solid line.
How does/should map rendering software prevent artifacts of this kind from occuring?
The artifact is due the fact that the piece of border is drawn twice. Instead of trying to supress such artifacts, you could try to not draw border sections twice, by keeping a list of segments already drawn in memory, and if you encounter a stretch that's already drawn, you don't draw it again.
Your brush pattern colors some pixels black and leaves some pixels alone. Instead of leaving the pixel alone, can you set up your brush pattern to color those pixels white (or whatever your background color is)?
Another possibility is to always draw your county borders twice -- once with a solid white pattern, and again with the brush pattern of your choice.
I suppose they break their border lines into segments, then remove the overlaps.
This is mostly a geometric problem, not a drawing problem.
Instead of going with a dashed line, you could do it Zip-a-tone style, like this:
Zip-a-tone was this graphic art stuff that was basically a sticky sheet of plastic with a regular (printable) pattern of dots on it. To use it, you would lay a big sheet of it over your drawing and cut it around the areas on your drawing that you wanted zip-a-toned, and then peel off the parts you didn't want.
For this image, I just went with an alternating checkerboard pattern, with the lines two pixels wide. Because all the lines are drawn from one big (virtual) block of this checkerboard pattern, you never have to worry about weird artifacts at the joints or any overlap effects.
Angled lines are a bit tricky, but basically you imagine the edges of the line sort of cutting through pixels, and thus you draw them at the appropriate shade of grade instead of full black (in the case of the 45 degree line here, the pixels are drawn with RGB(170, 170, 170), but any angle could be rendered with appropriate shades).
I'm not sure if GDI+ could do this easily using the textured brushes, but maybe. Otherwise you'd have to custom-code it. The advantage of this method over just solid gray lines would be that this would allow some of the background to show through.
This is an interesting question that I never really thought about. I think the only real solution is to render the entire complex figure as a series of lines or paths that do not overlap anywhere. I'm not surprised that GDI+ doesn't handle this situation in any automatic way.