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.
Related
I am getting difficulties for making this color view.
As you can see, this is not a single color.
I am struggling to get this colored view but seems like my skill is not enough for getting this color.
I am always eager to learn but for this time, I don't know how to I get this color.
The bars you are pointing to are nearly saturated magenta, roughly #ff64ff. However, they also have a bit of linear gradient on them to give them the tube shape, and a magenta "shadow" to give them glow effect. How to get them would be very dependent on the system you are using to draw them.
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 using 4-Way floodfill algorithm.
I have a transparent image with black out line.
That is staring point image(without color).
And after filling the color in this image it look like this
Please help me and let me know what can i do for proper fill.
I used and implemented myself FloodFill in other projects and the algorithm goes trough the whole draw, looking for closed spaces and then draw inside (or outside) them.
Your problem happens with every tool in the world that fills a draw, and the problem is the same, the spaces are not 100% closed.
The floodfill algorithm goes pixel by pixel and when it detect a black pixel, it stops. For example, the arm of the scuba driver is not thick enough or it has holes on it, and the flood fill algorithm manages to go trough it and not detect it as an empty space.
Nobody here can tell you why unless we take your project and analyse it, so the best I can offer is a guideline about where your error could be.
I tried the code with an image that has a very precise defined border around it (from here) and it seems to work OK with that image. I suggest perhaps that if you zoom into your image that there is some grey aliasing around the edges which won't get filled. Perhaps the algorithm has a threshold function that can be tweaked?
Try setting the andTolerance value (I tried 4 which seemed to improve my example).
//Call function to flood fill and get new image with filled color
UIImage *image1 = [self.image floodFillFromPoint:tpoint withColor:newcolor andTolerance:4];
We are building an iPad kids application in which a kid is requested to color different shapes with specific color. For example, consider an image with sky and trees , etc. all overlapping and a kid has selected a color for example "Blue" and then he taps the sky , the sky should turn to blue otherwise it should say "wrong color"
My questions are:
1- How to implement the coloring of the sky only with the selected color. We have implemented a Coco2d Floodfilling but it is too slow.
2- How to tie each part of the image with a specific right color. We suggested loading a fully colored image in a background layer and testing it at the tap .... BUT how to implement it.
Thanks
Are the shapes originally vectorial? If so, a solution would be to work directly with them as vectors, parsing them into CoreAnimation shapes.
You can give a try to SVGKit or get some inspiration from it. You'll get CAShapeLayers where you can change the fillColor property.
I believe that this way would be much more responsive (and the app size much more lighter) than doing tricks with images ;-)
I am creating a custom button that needs to be able to glow to a varying degree
How would I use these pictures to make a button that 'glows' the diamond when it is pressed, and have this glow gradually fade back to inert state?
I want to churn out several different colours of diamond as well... I am hoping to generate all different coloured diamonds from the same stock images presented here.
I would like to get my head around the basic methods available, in enough detail that I can see each one through and make a decision which path to take...
My tangled efforts so far... ( I will delete all of this, or move it into possibly several answers as a solution unfolds... )
I can see 3 potential solution paths:
GL
it looks as though GL has everything it takes to get complete fine-grained control over the process, although functions exposed by core graphics come tantalisingly close, and that would save several hundred lines of code spread over a bunch of source files, which seems a bit ridiculous for such a basic task.
core graphics, and core animation to accomplish the blending
documentation goes on to say
Anything underneath the unpainted samples, such as the current fill color or other drawing, shows through.
so I can chroma-key mask the left image, setting {0,0,0} ie Black as the key.
this at least secures a transparent background, now I have to work on making it yellow instead of grey.
so maybe I could have started instead with setting a yellow back colour for my image context, then use some CGContextSetBlendMode(...) to imprint the diamond on the yellow, THEN use chroma-key masking to get a transparent background
ok, this covers at least getting the basic unlit image on-screen
now I could overlay the sparkly image, using some blend mode, maybe I could keep it in its current greyscale state, and that would just boost the colours of the original
only problem with this is that it is a lot of heavy real-time blending
so maybe I could pre-calculate every image in the animation... this is looking increasingly mucky...
Cocos2D
if this allows me to set the blend mode to additive blending then I could just composite the glowing image over the original image with an appropriate Alpha setting.
After digging through a lot of documentation, the optimal solution seems to be to use core graphics functions to get the source images into a single 2-component GL texture, and then use GL to blend between them.
I will need to pass a uniform value glow_factor into the shader
The obvious solution might seem to simply use
r,g,b = in_r,g,b * { (1 - glow_factor) * inertPixel + glow_factor * shinyPixel }
(where inertPixel is the appropriate pixel of the inert diamond etc)...
it looks like I would also do well to manufacture my own sparkles and add them over the top; a gem should sparkle white irrespective of its characteristic colour.
After having looked at this problem a little more, I can see several solutions
Solution A -- store the transition from glow=0 to glow=1 as 60 frames in memory, then load the appropriate frame into a GL texture every time it is required.
this has an obvious benefit that a graphic designer could construct the entire sequence and I could load it in as a bunch of PNG files.
another advantage is that these frames wouldn't need to be played in sequence... the appropriate frame can be chosen on-the-fly
however, it has a potential drawback of a lot of sending data RAM->VRAM
this can be optimised by using glTexSubImage2D; several frames can be sent simultaneously and then unpacked from within GL... in fact maybe the entire sequence. if this is so, then it would make sense to use PVRT texture compression.
iOS: playing a frame-by-frame greyscale animation in a custom colour
Solution B -- load glow=0 and glow=1 images as GL textures, and manually write shader code that takes in the glow factor as a uniform and performs the blend
this has an advantage that it is close to the wire and can be tweaked in all sorts of ways. Also it is going to be very efficient. This advantage is that it is a big extra slice of code to maintain.
Solution C -- set glBlendMode to perform additive blending.
then draw the glow=0 image image, setting eg alpha=0.2 on each vertex.
then draw the glow=1 image image, setting eg alpha=0.8 on each vertex.
this has an advantage that it can be achieved with a more generic code structure -- ie a very general ' draw textured quad / sprite ' class.
disadvantage is that without some sort of wrapper it is a bit messy... in my game I have a couple of dozen diamonds -- at any one time maybe 2 or 3 are likely to be glowing. so first-pass I would render EVERYTHING ( just need to set Alpha appropriately for everything that is glowing ) and then on the second pass I could draw the glowing sprite again with appropriate Alpha for everything that IS glowing.
it is worth noting that if I pursue solution A, this would involve creating some sort of real-time movie player object, which could be a very useful reusable code component.