Using DirectX I'm rendering textured polygons (orthographically) so they act as HUD sprites. Now I'm not sure how would I go about implementing sprite masking in this sytem?
So basically say I have a sprite, how can I make it render only in a given portion of the screen which I define? And if a part of it moves outside this portion of the screen you don't see it?
Scissor Test.
http://msdn.microsoft.com/en-us/library/ee422196(VS.85).aspx
You're looking for what is called a viewport. considering you did not specify which DirectX and which language you're using, I'll have to point to the DirectX9 spec
Related
I need to be able to interact with a representation of a cilinder that has many different parts in it. When the users taps over on of the small rectangles, I need to display a popover related to the specific piece (form).
The next image demonstrates a realistic 3d approach. But, I repeat, I need to solve the problem, the 3d is NOT required (would be really cool though). A representation that complies the functional needs will suffice.
The info about the parts to make the drawing comes from an API (size, position, etc)
I dont need it to be realistic really. The simplest aproximation would be to show a cilinder in a 2d representation, like a rectangle made out of interactable small rectangles.
So, as I mentioned, I think there are (as I see it) two opposite approaches: Realistic or Simplified
Is there a way to achieve a nice solution in the middle? What libraries, components, frameworks that I should look into?
My research has led me to SceneKit, but I still dont know if I will be able to interact with it. Interaction is a very important part as I need to display a popover when the user taps on any small rectangle over the cylinder.
Thanks
You don't need any special frameworks to achieve an interaction like this. This effect can be achieved with standard UIKit and UIView and a little trigonometry. You can actually draw exactly your example image using 2D math and drawing. My answer is not an exact formula but involves thinking about how the shapes are defined and break the problem down into manageable steps.
A cylinder can be defined by two offset circles representing the end pieces, connected at their radii. I will use an orthographic projection meaning the cylinder doesn't appear smaller as the depth extends into the background (but you could adapt to perspective if needed). You could draw this with CoreGraphics in a UIView drawRect.
A square slice represents an angle piece of the circle, offset by an amount smaller than the length of the cylinder, but in the same direction, as in the following diagram (sorry for imprecise drawing).
This square slice you are interested in is the area outlined in solid red, outside the radius of the first circle, and inside the radius of the imaginary second circle (which is just offset from the first circle by whatever length you want the slice).
To draw this area you simply need to draw a path of the outline of each arc and connect the endpoints.
To check if a touch is inside one of these square slices:
Check if the touch point is between angle a from the origin at a.
Check if the touch point is outside the radius of the inside circle.
Check if the touch point is inside the radius of the outside circle. (Note what this means if the circles are more than a radius apart.)
To find a point to display the popover you could average the end points on the slice or find the middle angle between the two edges and offset by half the distance.
Theoretically, doing this in Scene Kit with either SpriteKit or UIKit Popovers is ideal.
However Scene Kit (and Sprite Kit) seem to be in a state of flux wherein nobody from Apple is communicating with users about the raft of issues folks are currently having with both. From relatively stable and performant Sprite Kit in iOS 8.4 to a lot of lost performance in iOS 9 seems common. Scene Kit simply doesn't seem finished, and the documentation and community are both nearly non-existent as a result.
That being said... the theory is this:
Material IDs are what's used in traditional 3D apps to define areas of an object that have different materials. Somehow these Material IDs are called "elements" in SceneKit. I haven't been able to find much more about this.
It should be possible to detect the "element" that's underneath a touch on an object, and respond accordingly. You should even be able to change the state/nature of the material on that element to indicate it's the currently selected.
When wanting a smooth, well rounded cylinder as per your example, start with a cylinder that's made of only enough segments to describe/define the material IDs you need for your "rectangular" sections to be touched.
Later you can add a smoothing operation to the cylinder to make it round, and all the extra smoothing geometry in each quadrant of unique material ID should be responsive, regardless of how you add this extra detail to smooth the presentation of the cylinder.
Idea for the "Simplified" version:
if this representation is okey, you can use a UICollectionView.
Each cell can have a defined size thanks to
collectionView:layout:sizeForItemAtIndexPath:
Then each cell of the collection could be a small rectangle representing a
touchable part of the cylinder.
and using
collectionView:(UICollectionView *)collectionView
didSelectItemAtIndexPath:(NSIndexPath *)indexPath
To get the touch.
This will help you to display the popover at the right place:
CGRect rect = [collectionView layoutAttributesForItemAtIndexPath:indexPath].frame;
Finally, you can choose the appropriate popover (if the app has to work on iPhone) here:
https://www.cocoacontrols.com/search?q=popover
Not perfect, but i think this is efficient!
Yes, SceneKit.
When user perform a touch event, that mean you knew the 2D coordinate on screen, so your only decision is to popover a view or not, even a 3D model is not exist.
First, we can logically split the requirement into two pieces, determine the touching segment, showing right "color" in each segment.
I think the use of 3D model is to determine which piece of data to show in your case if I don't get you wrong. In that case, the SCNView's hit test method will do most of work for you. What you should do is to perform a hit test, take out the hit node and the hit's local 3D coordinate of this node, you can then calculate which segment is hit by this touch and do the decision.
Now how to draw the surface of the cylinder would be the only left question, right? There are various ways to do, for example simply paint each image you need and programmatically and attach it to the cylinder's material or have your image files on disk and use as material for the cylinder ...
I think the problem would be basically solved.
Although I am quite experienced with most frameworks in iOS, I have no clue when it comes to 3D modelling. I even worked with SpriteKit, but never with something like SceneKit.
Now a customer wants a very ambitious menu involving a 3D object, an 'icosahedron' to be exact. I want it to look something like this:
So I just want to draw the lines, and grey out the 'see-through' lines on the back. Eventually I want the user to be able to freely rotate the object in 3D.
I already found this question with an example project attached, but this just draws a simple cube: Stroke Width with a SceneKit line primitive type
I have no clue how to approach a more complex shape.
Any help in the right direction would be appreciated! I don't even need to use SceneKit, but it seemed like the best approach to me. Any other suggestions are welcome.
to build an icosahedron you can use SCNSphere and set its geodesic property to YES.
Using shader modifiers to draw the wireframe (as described in Stroke Width with a SceneKit line primitive type) is a good idea.
But in your case lines are not always plain or dotted — it depends on the orientation of the icosahedron. To solve that you can rely on gl_FrontFacing to determine whether the edge belongs to a front-facing or back-facing triangle.
I'm using XNA 3.1
I have recently created a 2D Heads Up Display (HUD) by using Components.Add(myComponent) to my game. The HUD looks fine, showing a 2D map, crosshairs and framerate counter. The thing is, whenever the HUD is on screen the 3D objects in the game no longer draw correctly.
Something further from my player might get drawn after something closer, the models sometimes lose definition when I walk past them. When I remove the HUD all is drawn normally.
Are their any known issues regarding this that I should be aware of? How should I draw a 2D HUD over my 3D game area?
This is what it looks like without a GameComponent:
And here's how it looks with a GameComponent (in this case it's just some text offscreen in the upper left corner that shows framerate), notice how the tree in the back is appearing in front of the tree closer to the camera:
You have to enable the depth buffer:
// XNA 3.1
GraphicsDevice.RenderState.DepthBufferEnable = true;
GraphicsDevice.RenderState.DepthBufferWriteEnable = true;
// XNA 4.0
GraphicsDevice.DepthStencilState = DepthStencilState.Default;
SpriteBatch.Begin alters the state of the graphics pipeline:
SpriteBatch render states for XNA 3.1
SpriteBatch render states for XNA 4.0
In both versions depth buffering is disabled, that's what causes the issue.
Again, I cannot stress this enough:
Always make sure that ALL render states are correctly set before drawing any geometry.
BlendState
DepthStencilState
RasterizerState
Viewports
RenderTargets
Shaders
SamplerStates
Textures
Constants
Educate yourself on the purpose of each state and each stage in the rendering pipeline. If in doubt, try resetting everything to default.
I want to make a 3D metal compass in iOS which will have a movable cover.
That is when you touch it by 3 fingers and try to move your fingers upward the cover keeps moving with your fingers and after certain distance it gets opened.Once you pull it down using 3 fingers again, it gets closed. I have attached a sketch about what I'm thinking.
Is it possible using core animations and CALayers? Or would I have to use OpenGL ES?
First you should obviously create a textured 3d model in app like 3Ds Max or Maya. Then export it to some suitable format. The simplest one is OBJ (there are lots of examples about how to load it). There are two options about animation:
Do animation manually by rotating the cover object. It's probably the easiest way to do that.
Create animation in you 3D editor and then interpolate between frames. By doing this you can get much more realistic view. However in this case OBJ format is not suitable, but COLLADA is. To load it I suggest to use Assimp library.
And if you don't need some advanced interraction another option is to use pseude 3D: just pre render all the compass animation frames and use that animation applied to 2d texture.
I understand that I have to draw everything in draw(), and it's looping continuously.
But I don't want to draw texture again and again, for example I want to create a texture, draw something to texture (not spritebatch). than I will only draw that texture in draw().
Is it possible?
What can I use?
You have to draw again and again, as in short, if you dont it wont show. A wise man once wrote in a windows development book
Ask not why the text on your windows has to be constantly drawn, ask why it never used to be in DOS/Unix command line.
If something is placed over the area you're drawing too, and you dont redraw it, it just simply wont be there. You need to keep drawing it for it to be sustained on screen. Its done very quickly and wont hurt anything (especially if you're thinking in terms of background)
Not drawing it again is a performance optimisation. You should only do that if you really need to.
If you do need to do this, create a render target, draw your scene to the render target, and then draw your render target to the screen each frame (using SpriteBatch makes this easy) instead of your scene.
Take a look at this question about caching drawing using render targets.