The title of this question isn't great at explaining what I want to do, so have this gif of the effect I want to emulate: https://i.imgur.com/zRqTSqf.gif (quality of the gif is shite, ik, please bear with me)
I think I need to use the LoopOut() expression for well, the loop, but I don't know how to animate the colors like that. Do I assign different colors in a shape? I'm fairly new to motion graphics, so I'm not familiar with technical terms and all that. Any help/guidance is appreciated!
I would recommend the following:
Create the square shape you are looking for, as a shape layer with a stroke and no fill
Duplicate the shape layer, for example, 4 times
Apply the Trim Paths effect to these layers and distribute it as you wish (for example, if using 4 layers first one from 0 to 25, second one from 25 to 50, third 50 to 75 and fourth one 75 to 100%.
Set a different color for each layer
Create a new Null Object and assign the Slider Control effect to it
Set the Trim Paths Offset property to be driven by the Slider property of the Slider Control (using the pick whip from each layer)
Animating the Slider property of the Slider control in the Null Object, driving the color of all the sides.
Use masks to fix the possible glitches on the vertices and to make it look nice
you can then alt-click on the stopwatch of the Slider property inside the Slider Control of the Null Object and type LoopOut(). Make sure that the first and last keyframes are correct so once the looping is activated the end is the same as the beginning and you should be good to go!
I think this should more or less point you in a possible way of solving it, let me know if you need more help!
In Illustrator, draw a square with a stroke, no fill, and rotate it 45 degrees. And on a separate layer, draw 6 triangles in the desired colours. Example below:
Save as an AI file. Import this artwork into After Effects, setting Import Kind to Composition.
Set the composition length to 4 seconds.
Set the track matte for the triangles layer to the Alpha Matte of the square layer. (#1 in the above)
Open the rotation property of triangles, set a key frame on frame 1, then go to 4 seconds, and set a key frame of 1 rotation. (#2 in the above)
Precompose these layers, then apply a CC Light Burst 2.5 effect for the glow.
Result is as below.
Related
(a) what I have, (b) what I get, (c) what I want
I have a simple vector graphic in Inkscape, which consists of a rectangle, filled points and stars. Since the axis ranges are not really nice (the height equals approximatly 3 times the width of the picture) for a publication, I want to rescale the picture. However, I do not have the raw data, such that I can plot it again. How can I rescale my graphic (see figure (a)), such that the x-range is more wide (see figure (c)) without getting distortions (see figure (b))? In the end I want to create a PDF file out of it.
Any ideas on that?
Thanks for your help.
You can try to do it in 2 steps, using the Object -> Transform tool (Shift-Ctrl-M).
First, select everything, and with the transform tool select the Scale tab, and scale horizontally by, say, 300%. All figures will be distorted.
Now, unselect the rectangle, and scale horizontally again by 33.3%, but first click on Apply to each object separately. This will undo the distortion (but not the translation) of each object.
Note that 300% followed by 33.3% should leave the individual objects with the same size.
Documentation here.
I created a flowchart in InkScape in which each shape is filled with a linear gradient.
Some shapes share the same gradient tones but when I created them via copy&past did not know that gradients could be transformed during edit, I thought that copy&pasting a shape simply copy the entire object and each colors.
Anyway, it resulted in shapes that changes background gradient during re-positioning. After several searches I discovered that this is caused by a wrong position of "Gradient Editor Tool" of each one. In other words I moved objects but start/end of each gradient remained in place.
Please, how to quickly reposition gradient direction/start/end of each shape, maybe centering it on each one? I would avoid to manually reposition each one...
Thanks
Inkscape provides a toggle button to move the gradients along with the objects.
Activating this button during any coying or moving carries the gradient with it to the new location. (Actually it copies the gradient.)
When in cocos2d-x you set ResolutionPolicy::SHOW_ALL then it might appear black areas from top-bottom or from left-right sides. Can I cover the black area with some nice images?
I don't think you can just add something into those back areas.
Instead the solution is to build a scene which already contain the nice images you want to add. The steps are:
Use this inside your AppDelegate::applicationDidFinishLaunching() to detect screen size:
CCSize frameSize = pEGLView->getFrameSize();
Set a design resolution proportional to this frameSize maintaining its aspect ratio.
Put your "content" in the mid. Then, you have to calculate where are the "black areas" and add sprites to cover them. Keep in mind that for different screen the holes can be different, so you need to do some maths there and properly cover different hole sizes.
So, doing ResolutionPolicy::SHOW_ALL sets the openGL view to that size. That's why that can't be done with that.
On the other hand, there are many ways to tackle this.
What i did was :
1. Don't set the ResolutionPolicy.
Use a layer for those nice images/effects.
Create a new layer in that same scene and set the width and height of that layer according to aspect ratio of your content. And make this as your primary game view.
I'm having a problem with creating an array that gives me the information about 2 images that are drawn upon each other.
What I have is 1 image as background (the sea) and 1 image as foreground (landscape) the landscape is not so big as the sea, so when drawn upon each other you can see the sea as well as the landscape on it.
Now I want to make an array that sets me an 0 if it is the sea and a 1 if it is the landscape. So I could use
this array to do some collision detection later. The problem is I don't find how to make a bytearray from it.
off length * width of the images.
I have both images in an QImage, but I don't find how to create the array with a for loop or something.
Both images are drawn upon each other with the QPainter function.
Can someone help me?
Kind regards,
If you draw the two images upon each other with the QPainter class, you loose any information about them, they are just drawings now. you must create methods and objects to implement your school project. I know that you can't use the QGraphicsView, but what you need is to look how qgraphicsview works so you will have a bit of information on how to implement your own collision system.
1 - you need to keep the Retangle of your drawings ( all of them ) saved somewhere. a QList will do.
2 - you need the Positions of your Drawings too, so y ou know where they are, besides the retangles.
with the positions, and the rectangles, all you need to do is check if one rectangle intersects another.
I did it with 2 forloops and used black and blue to determine the fore and background. So I can only use black and blue.
As seen in the image
I draw set of contours (polygons) as GL_LINE_STRIP.
Now I want to select curve(polygon) under the mouse to delete,move..etc in 3D .
I am wondering which method to use:
1.use OpenGL picking and selection. ( glRenderMode(GL_SELECT) )
2.use manual collision detection , by using a pick-ray and check whether the ray is inside each polygon.
I strongly recommend against GL_SELECT. This method is very old and absent in new GL versions, and you're likely to get problems with modern graphics cards. Don't expect it to be supported by hardware - probably you'd encounter a software (driver) fallback for this mode on many GPUs, provided it would work at all. Use at your own risk :)
Let me provide you with an alternative.
For solid, big objects, there's an old, good approach of selection by:
enabling and setting the scissor test to a 1x1 window at the cursor position
drawing the screen with no lighting, texturing and multisampling, assigning an unique solid colour for every "important" entity - this colour will become the object ID for picking
calling glReadPixels and retrieving the colour, which would then serve to identify the picked object
clearing the buffers, resetting the scissor to the normal size and drawing the scene normally.
This gives you a very reliable "per-object" picking method. Also, drawing and clearing only 1 pixel with minimal per-pixel operation won't really hurt your performance, unless you are short on vertex processing power (unlikely, I think) or have really a lot of objects and are likely to get CPU-bound on the number of draw calls (but then again, I believe it's possible to optimize this away to a single draw call if you could pass the colour as per-pixel data).
The colour in RGB is 3 unsigned bytes, but it should be possible to additionally use the alpha channel of the framebuffer for the last byte, so you'd get 4 bytes in total - enough to store any 32-bit pointer to the object as the colour.
Alternatively, you can create a dedicated framebuffer object with a specific pixel format (like GL_R32UI, or even GL_RG32UI if you need 64 bits) for that.
The above is a nice and quick alternative (both in terms of reliability and in implementation time) for the strict geometric approach.
I found that on new GPUs, the GL_SELECT mode is extremely slow. I played with a few different ways of fixing the problem.
The first was to do a CPU collision test, which worked, but wasn't as fast as I would have liked. It definitely slows down when you are casting rays into the screen (using gluUnproject) and then trying to find which object the mouse is colliding with. The only way I got satisfactory speeds was to use an octree to reduce the number of collision tests down and then do a bounding box collision test - however, this resulted in a method that was not pixel perfect.
The method I settled on was to first find all the objects under the mouse (using gluUnproject and bounding box collision tests) which is usually very fast. I then rendered each of the objects that have potentially collided with the mouse in the backbuffer as a different color. I then used glReadPixel to get the color under the mouse, and map that back to the object. glReadPixel is a slow call, since it has to read from the frame buffer. However, it is done once per frame, which ends up taking a negligible amount of time. You can speed it up by rendering to a PBO if you'd like.
Giawa
umanga, Cant see how to reply inline... maybe I should sign up :)
First of all I must apologize for giving you the wrong algo - i did the back face culling one. But the one you need is very similar which is why I got confused... d'oh.
Get the camera position to mouse vector as said before.
For each contour, loop through all the coords in pairs (0-1, 1-2, 2-3, ... n-0) in it and make a vec out of them as before. I.e. walk the contour.
Now do the cross prod of those two (contour edge to mouse vec) instead of between pairs like I said before, do that for all the pairs and vector add them all up.
At the end find the magnitude of the resulting vector. If the result is zero (taking into account rounding errors) then your outside the shape - regardless of facing. If your interested in facing then instead of the mag you can do that dot prod with the mouse vector to find the facing and test the sign +/-.
It works because the algo finds the amount of distance from the vector line to each point in turn. As you sum them up and you are outside then they all cancel out because the contour is closed. If your inside then they all sum up. Its actually Gauss's Law of electromagnetic fields in physics...
See:http://en.wikipedia.org/wiki/Gauss%27s_law and note "the right-hand side of the equation is the total charge enclosed by S divided by the electric constant" noting the word "enclosed" - i.e. zero means not enclosed.
You can still do that optimization with the bounding boxes for speed.
In the past I've used GL_SELECT to determine which object(s) contributed the pixel(s) of interest and then used computational geometry to get an accurate intersection with the object(s) if required.
Do you expect to select by clicking the contour (on the edge) or the interior of the polygon? Your second approach sounds like you want clicks in the interior to select the tightest containing polygon. I don't think that GL_SELECT after rendering GL_LINE_STRIP is going to make the interior responsive to clicks.
If this was a true contour plot (from the image I don't think it is, edges appear to intersect) then a much simpler algorithm would be available.
You cant use select if you stay with the lines because you would have to click on the line pixels rendered not the space inside the lines bounding them which I read as what you wish to do.
You can use Kos's answer but in order to render the space you need to solid fill it which would involve converting all of your contours to convex types which is painful. So I think that would work sometimes and give the wrong answer in some cases unless you did that.
What you need to do is use the CPU. You have the view extents from the viewport and the perspective matrix. With the mouse coord, generate the view to mouse pointer vector. You also have all the coords of the contours.
Take the first coord of the first contour and make a vector to the second coord. Make a vector out of them. Take 3rd coord and make a vector from 2 to 3 and repeat all the way around your contour and finally make the last one from coord n back to 0 again. For each pair in sequence find the cross product and sum up all the results. When you have that final summation vector keep hold of that and do a dot product with the mouse pointer direction vector. If its +ve then the mouse is inside the contour, if its -ve then its not and if 0 then I guess the plane of the contour and the mouse direction are parallel.
Do that for each contour and then you will know which of them are spiked by your mouse. Its up to you which one you want to pick from that set. Highest Z ?
It sounds like a lot of work but its not too bad and will give the right answer. You might like to additionally keep bounding boxes of all your contours then you can early out the ones off of the mouse vector by doing the same math as for the full vector but only on the 4 sides and if its not inside then the contour cannot be either.
The first is easy to implement and widely used.