Examples of what i'm going to need:
I'm using cocos2d to draw a CCTMXTiledMap, on those tiles i'll have to draw the LOS triangle.
How would i test if the player is within that triangle, taking obstacles into account?
How would i draw the line of sight area like in the examples above?
BTW, i wasn't sure if this should have been posted here or on gamedev, don't be mad.
You may wish to look at point-in-polygon algorithms such as the ray casting algorithm described here.
You can break up the triangle to account for obstacles, or just make a more complex polygon. You should be able to find an implementation to suit your needs online.
You may also want to take a look at this article for some inspiration. You can maintain a tree like structure, a root triangle (or fulcrum) that can be used to determine whether a point is in general line of sight, with the children (triangles) taking obstacles into account. That way you can quickly eliminate more complex checks.
In the image below the dark blue dots are quickly eliminated from further checking as they do not fall within the root viewing triangle.
Related
Is it possible to have a physics object in GameMaker Studio use precise collisions?
Here's some context for my question. I'm making a pirate game where the player sails around a large ocean with a number of islands. I've been using the physics engine to control the movement of the ship, and that is working well. However, the problem arises when trying to introduce collisions between the ship and the various islands. As far as I can tell, the underlying physics fixtures can only be formed into fairly simple shapes. Specifically, the collision shape editor is limited to 12 points, and only convex shapes. This is a problem, because many of my islands are relatively complicated non-convex shapes, and aren't necessarily a single piece. It would be nice to be able to use the island sprite as a precise collision mask, as would be possible for non physics based objects.
Is there a way to do this, or a possible work-around that I'm missing? Here's an example of one of my islands:
I can see two solutions to your problem.
1 - The easiest, but performance-unfriendly.
In the sprite editor, click "Modify mask". There should be a "precise collision checking" box you can tick. This means that your sprite will be checked pixel by pixel for collisions. As you can guess, this is not performance friendly, but will do exactly what you want.
2 - The one I would recommend.
What you could do is just draw the island sprites, either through the background or via a dedicated object, and then create some simple shape objects (rectangle, circle and diamond), that would be invisible, and place them over your islands in the room editor. (Don't forget that you can stretch them).
These simple shaped objects would be the ones to check for collisions.
I used this technique make a hitbox for complex-shaped clouds in one of my games, so I know it works.
I believe that the island you show us can be fairly well covered with a few ovals and a long rectangle.
Bonus : after doing that graphically, you can copy the creation code of the shapes from the room create event to the island create event to repeat for multiple identical islands. Just don't forget the position/angle offset !
By using the Shape options when defining the collision shape, you can have any kind of Convex polygon as your collision shape. Example:
The spot where you choose the Shape option is in red.
After you select that option, you can just click & drag to add/edit a vertex to the polygon. Just bear in mind, it has to be a convex polygon, GameMaker is very strict about that. You can also remove vertices by right clicking on them.
I am working with kinect in openframework using the ofxKinect addon, which is great and plenty fun!
Anyway I am looking for some pointers or a direction when dealing with multiple bodies on the screen. I was thinking of making a rect around each detected body and when the rects intersect something could happen, an effect or anything.
So what I am looking for are ideas or something that could point me to the right direction of detecting multiple bodies when using a kinect.
Right now based on the depth image I get from the kinect I go through each pixel and create a bunch of smaller rectangles with a padding and group them in a larger rectangle bound if they are separate from another rectangle group. This is not ideal as it only deals with the pixel values and is not really seperating bodies from eachother and is not giving me the results I am looking for.
So any ideas would be greatly appreciated!
If you want to use ofxKinect a quick solution would be to threshold on depth and assume bodies and no other objects will be within a depth range. This should make it easy to use the OpenCV's contour finder to isolate the outlines of the bodies and get the bounding rectangles. If the rectangles intersect(and ofRectangle already does the math you), trigger the reaction you need. Also don't forget to do that once if the effect isn't showing already, otherwise you will trigger the effect multiple times per second while the two bodies' bounding rectangles intersect.
You could try something a bit more hardcore and using ofxCv(not just ofxOpenCV) to tap into the HoG functionality. This is slow in itself and not ideal with the depth map, but hopefully you can run in every few seconds just to detect a person and the depth, then keep tracking that movement.
Personally, if you want to track people with the Kinect I recommend using ofxOpenNI as if already provides the scene segmentation feature and even if you don't track the skeletons you can still get useful information like the pixels pertaining to each body and they're centre of mass. I'm guessing Microsoft KinectSDK has a similar feature and there should be an oF addon, but it's windows only.
ofxKinect/libfreenect does not offer any people detection features, so you will need to roll your own.
I've just got started with physics. I'm using Java, though language does not matter obviously. Now I though I'd do something like this:
A ball with a certain speed, radius and mass hits a rectangle with a certain mass, width and height. Depending on where the ball hits the rectangle (how high up), and all the properties the ball and the rectangle have that i just mentioned, there will be different outcomes of the situation.
These are the four possible outcomes:
The ball bounces back because the rectangle was too heavy
The rectangle starts to wobble, but then goes back to normal
The rectangle falls to the right
The ball strikes through making the rectangle fall to the left
Please note, I don't expect you to write a program for me. I understand it is a lot to think off. But I have no idea how to start. I would really appreciated some guide lines and links to further reading about this (I was not sure what to google to find info about this.)
And also, I'm doing this to learn, so don't tell me to use an engine or anything like that.
You are trying to build a simple physics simulator. This is a pretty involved problem, and you'll have to learn a certain amount of physics along the way.
I suggest you develop the simulator to handle these situations, roughly in this order:
An object moves through space (constant velocity, no gravity).
An object moves under the influence of a constant force (such as gravity).
An object moves with a constraint (e.g. a pendulum, a rolling square).
An object slides across a surface, with friction (both static and kinetic).
Two objects collide inelastically (they stick).
Two objects collide elastically (they bounce).
Once you have all of these, you will be able to simulate your ball and rectangle.
I've seen quite a bit of questions regarding how to draw isometric tiles, and most all point at being drawn back to front, top down. However I'm trying to find a way to prevent clipping with a single isometric image.
While normally drawing a sprite ontop of a single image would not prevent overdrawing on walls and such, I split up the image into 3 layers. A floor, lower wall, and top wall. Where the player checks the floor for collision, is drawn in front of the lower wall always, and drawn behind the top wall always. The result looks like the following
While this seems to work decently well, I'd like to know what the most efficient way to draw these sort of isometric scenes are. I've considered tiles, however that raises the question of how to draw multi-tiled buildings and such. If tiling becomes a better option I will create a new question regarding those questions. For now lets assume I'm using a single image broken into layers.
This is somewhat easier, however, for my artist. To be able to draw a single scene in isometric, and split it up into layers, eliminating the need for a map creator. And then using pixel collision to get precise collision with the enviroment.
Is using a multi-layered scene even a good approach for this? My biggest concern is preventing overdrawing and breaking perspective. I've also seen many good examples of drawing everything using tiles, however then I'm limited to a certain scale, and that arises even more questions. Do you know of the best way to approach this? Should I use tiles instead of a single image split into layers?
I plan to code this in either MonoGame or Processing.
(I would have posted this on gamedev but I can not post images there)
I am making an app that allows the user to draw on the screen with his finger in different colors. The drawings are drawn with UIBezierPaths but I need an eraser. I did have an eraser that was just a path with the background image as the color but this method causes memory issues. I would like to delete the points from any path that is drawn on when eraser is selected.
Unfortunately UIBezierPath doesn't have a subtraction function so I want to make my own. So if eraser is selected, it will look at all the points that should be erased and see if any of the existing paths contain those points, then subdivide the path leaving a blank spot. But it should be able to see how many points in a row to delete not do it one at a time. In theory it makes sense but I'm having trouble getting started on the implementation.
Anyone have any guidance to set me on the right 'path'?
Upon first glance, it appears that you could do hit detection on a UIBezierPath by simply using containsPoint:. That works fine if you want to determine whether the point is contained in the fill of a UIBezierPath, but it does not work for determining whether only the stroke of the UIBezierPath intersects the point. Detecting whether or not a given point is in the stroke of a UIBezierPath can be done as described in the "Doing Hit-Detection on a Path" section at the bottom of this page. Actually, the code sample they give could be used either way. The basic idea is that you have to use the Core Graphics method CGContextPathContainsPoint.
Depending on how large the eraser brush is, you will probably want to check several different points on the edge of the brush circle to see if they intersect the curve, and you'll probably have to iterate through your UIBezierPaths until you get a hit. You should be able to optimize the search by using the bounds of the UIBezierPath.
After you detect that a point intersects a UIBezierPath, you must do the actual split of the path. There appears to be a good outline of the algorithm in this post. The main idea there is to use De Casteljau's algorithm to perform the subdivision of the curve. There are various implementations of the algorithm that you should be able to find with a quick search, including some in C++.