I'm planning on implementing a new set of figures in my game: plain circles. The number of drawn sprites (in this case circles) starts with 2-3, and can go up endlessly (potentially). The maximum will probably be around 60 though. In total there will have to be 5 types of circles, each with a different color and probably size too. Now seeing as I won't implement it until monday I thought I'd ask it at stackoverflow.
Does anybody already know which method is faster?
Bitmaps are almost always faster than any kind of draw. With the right preparation drawing a bitmap is simply dumping memory to the screen. Drawing a circle involves a significant number of calculations, including anti-aliasing. I presented a paper which covered this at JavaOne 2009, but papers that old seem to have been removed from the site.
It does depend on how big your bitmap would need to be, but for sizes under 10 pixels bitmap sprites are much faster than even simple graphic operations like drawing crosses and lines. You also need to make sure that your sprite won't require any kind of transform when it is drawn, and that it is a form compatible with the screen memory.
If every circle is to be a different color or thickness, or worse a different size, then that's another matter. The cost of creating each bitmap would outweigh the savings.
You should also remember the first rule of optimization: don't do it unless you have to.
Related
In short, I'm making a simulation where I have a bunch of creatures that can see each other. The way I want to do this is to capture an area around each creature and give it to their neural network, and make them evolve to recognize their surroundings. I am coding this using LibGDX, and I don't plan on making screenshots every single frame because I can imagine that that is already a very poor idea. However, the problem is that I don't know how to get the pixels inside a defined square without capturing the entire screen and then cherry picking what I want for each creature, which will cause a MASSIVE lag spike, since the area these creatures will be in is 2000x2000, and therefore 12 million different values (4 million RGB values).
Each creature is about 5 pixels (width and height), so my idea is to give them a 16x16 area around them, which is why iterating through the entire frame buffer won't work, it would pointlessly iterate through millions of values before finding the ones I asked for.
I would also need to be able to take pictures outside of the screen (as in, the part outside the window's boundaries), if that is even possible.
How can I achieve this? I'm aiming for performance, but I do not mind distributing the load between multiple frames or even multithreading.
The problem is you can't query pixels in a framebuffer.
You can capture a texture from a framebuffer, and you can convert a texture to a pixmap.
libgdx TextureRegion to Pixmap
You can then getPixel(int x, int y) against the pixmap.
However, maybe going the other way would be better.
Start with a pixmap, work with the pixmap, and for each frame convert the pixmap to a texture and render that texture fullscreen. This also removes the need for the creatures environment to match the screen resolution (although you could still set it up like that).
I have a program that utilizes Path2D.Float to draw a vector object (a large fractal design). My code allows zooming and panning. I have an axis object that has methods to convert world coordinates (pairs of doubles) to display coordinates (pairs of floats) based on the current scaling settings (stored in the axis object).
Anyways, the vector graphic is large and detailed and contains many line segments in world coordinates. Each time the user zooms or pans, new Path2D objects are created and rendered to the screen.
Everything is perfectly smooth when zoomed out. The problem occurs when I zoom in to a certain depth. Apparently the Path2D lines get very long and this slows down their rendering (even though the vast majority is outside the viewing area!). It's not my conversion algorithms consuming resources. I profiled it and it's definitely the Java graphics drawing algorithm that's slowing down due to the size of the lines in comparison to the small clipping region.
I was hoping there was a way to get Java to deal with the clipping of large lines automatically. I do call setClip() from the graphics object before drawing. I don't see what's taking so much time. Is there something problematic/inefficient about the clipping algorithm when lines are long in comparison the clipping rectangle? I don't think I'm zooming so far that my conversion from world coordinates to display coordinates is causing overflow. I'll have to check for this. If that's the case I'll try using Path2D.double instead.
Anyways, any help appreciated. I'm sure I'll eventually figure this out but I hope someone that's encountered the same problem can give me a pointer so it doesn't take so long to figure out.
I've not used paths when zooming, but I have used them for drawing some very complex shapes with textures & gradients etc. Some issues I had were:
In my experience, I had to avoid creating new Path2D objects on a per frame basis because of performance issues, not just for their recreation execution, but because it caused a lot of garbage collection with generating & then dropping so many so quickly, which slowed things down. If your shape doesn't change, cache the generated path.
Avoid clipping with paths - where possible stick to rectangles - paths seem to give rough edges on curves and are more costly to use.
Even when clipping to smaller regions, simply asking to draw large regions could slow things down. Consider when the user zooms in to tessellate your shape, i.e. the shape is only as big as your viewport. Perhaps as you say maybe there is an issue with the clip function when dealing with large volume areas, so tessellation might help here.
I am making a game using LWJGL, and so far I decided to have 5 or 6 sprite sheets. It is like one for the blocks, one for the items, objects, etc. By doing that, I have sprite sheets with sprites that are closely related, and normally have the same size (in the case of blocks and items). But is this the better way? Or should I just throw everything on a single sprite sheet, with no organization whatsoever?
If I am doing it the right way, there is also another problem. For example, when you are in the map, I need to draw the blocks. But over the blocks, there can be electrical wires and other stuff - that are in a separated sprite sheet. This information, however, is stored in the same array. So normally I just iterate over it once, and each time, draw the block, and then the wire over it - switching sprite sheets twice each iteration. But I thought it might take some time to switch these, so maybe it would be more interesting to run the thing twice, first draw all the blocks, and then iterate again to draw the wires? To change the textures, I am using the SlickUtil Texture class, which has a bind method - really easy to use.
There is no "ideal"; there are simply the factors that matter for your needs.
Remember the reason why you use sprite sheets at all: because switching textures is too expensive to do per-object when dealing with 2D rendering. So as long as you're not switching textures for each sprite you render, you'll already be ahead of the game performance-wise.
The other considerations you need to take into account are:
Minimum user hardware specifications. Specifically, what is the minimum size of GL_MAX_TEXTURE_SIZE you want your code to work on? The larger your sprite sheets get, the greater your hardware requirements, since a single sprite sheet must be a texture.
This value is hardware-dependent, but there are some general requirements. OpenGL 3.3 requires 1024 at a minimum; pretty much every piece of GL 3.3 hardware gives 4096. OpenGL 4.3 requires a massive 16384, which is approaching the theoretical limits of floating-point texture coordinate capacity (assuming you want at least 8 bits of sub-pixel texture coordinate precision).
GL 2.1 has a minimum requirement of 64, but any actual 2.1 hardware people will have will offer between 512 and 2048. So pick your sprite sheet size based on this.
What you're rendering. You want to be able to render as much as possible from one sprite sheet. What you want to avoid is frequent texture switches. If your world is divided into layers, if you can fit your sprites for each layer onto their own sheet, you're doing fine. No hardware is going to choke on 20 texture changes; it's tens of thousands that are the problem.
The main thing is to render everything that uses a sheet all at once. Not necessarily in the same render call; you can switch meshes and shader uniforms/fixed-function state. But you shouldn't switch sheets between these renders until you've rendered everything needed for that sheet.
I am building a 2D top-down tile based game in Java. Naturally you can pan around and zoom in on the game, currently zooming in on 10 different levels, where each tile ranges 10x10 pixels to 100x100 pixels appropriately. Currently, the the tiles for each zoom level are stored in separate sprite sheets, read in at the startup of the program and stored in a buffered image array. I am sure this can't be the best way to go about this.
I am looking for any tips to enhance efficiency for the long-term, would it be better to have the 100x100 tiles only and scale them dynamically in java; somehow use vector graphics in java (I'm sure how, but I'm sure google could help me) or what?
Many thanks!
I'd go dynamic.
Normally in computer graphics you use matrices that, applied to the graphics context, modify everything you draw on it.
This is used to modify position, scale, rotation, etc. Rather than subtract the camera position to every tile, you apply the translation once to the graphics context, and then you draw your tiles in world position. The graphics context will take care of placing the tiles in the correct screen space.
I suggest you the following reads:
http://docs.oracle.com/javase/tutorial/2d/advanced/transforming.html
http://www.javalobby.org/java/forums/t19387.html
If you're doing fixed zooming (i.e. each zoom level is a fixed distance from the camer), as opposed to fluid zooming (the player can zoom in by 3.3x, 7.5x, and not just 1x, 2x, 3x, etc.) then it's massively wasteful to try to solve this by simply applying a zoom transform. It's tempting because that's the least complicated approach, and it's easy to understand from an implementation standpoint, but that means that at maximum zoom-out, you're going to be rendering an area that's 10x larger in the X direction, and 10x larger in the Y direction - so the area of the world that you have to render is 100x larger than at maximum zoom-in. I also doubt that you'll like the way your textures get squished by the hardware as you're zooming out. Computer graphics isn't the same as optics - subpixel rendering, and other things that happen in computer graphics aren't going to make your textures look very good if you hand that task off the the software/hardware.
Even if you do fluid zooming, I would still do level-of-detail textures, and dynamically swap them out depending on the distance between the world being rendered, and the camera.
Also, 10 zoom levels? Are you sure you really need 10 zoom levels? Zoom is usually used in 2D games to allow you to perform different activities at different levels of detail because a particular zoom level is especially well suited for a certain set of activities. I don't remember any 2D game that needed 10 zoom levels to accomplish this. 3-5 is the most I've ever seen, and I've never felt that it wasn't enough. It also seems like a lot of art work to produce the images at every zoom level for 10 zoom levels.
You're also likely going to find that applying an AffineTransform sounds like a good idea, but that it's extremely computationally expensive, and if you need 60fps performance, you're highly unlikely to achieve it this way. Don't take my word for it though, go try it and see how badly it falls over on itself.
I'm new to OpenGL. I'm using JOGL.
I would like to create a sky for my world that I can texture with clouds or stars. I'm not sure what the best way to do this is. My first instinct is to make a really big sphere with quadric orientation GLU_INSIDE, and texture that. Is there a better way?
A skybox is a pretty good way to go. You'll want to use a cube map for this. Basically, you render a cube around the camera and map a texture onto the inside of each face of the cube. I believe OpenGL may include this in its fixed function pipeline, but in case you're taking the shader approach (fixed function is deprecated anyway), you'll want to use cube map samplers (samplerCUBE in Cg, not sure about GLSL). When drawing the cube map, you also want to remove translation from the modelview matrix but keep the rotation (this causes the skybox to "follow" the camera but allows you to look around at different parts of the sky).
The best thing to do is actually draw the cube map after drawing all opaque objects. This may seem strange because by default the sky will block other objects, but you use the following trick (if using shaders) to avoid this: when writing the final output position in the vertex shader, instead of writing out .xyzw, write .xyww. This will force the sky to the far plane which causes it to be behind everything. The advantage to this is that there is absolutely 0 overdraw!
Yes.
Making a really big sphere has two major problems. First, you may encounter problems with clipping. The sky may disappear if it is outside of your far clipping distance. Additionally, objects that enter your sky box from a distance will visually pass through a very solid wall. Second, you are wasting a lot of polygons(and a lot of pain) for a very simple effect.
Most people actually use a small cube(Hence the name "Sky box"). You need to render the cube in the pre-pass with depth testing turned off. Thus, all objects will render on top of the cube regardless of their actual distance to you. Just make sure that the length of a side is greater than twice your near clipping distance, and you should be fine.
Spheres are nice to handle as they easily avoid distortions, corners etc. , which may be visible in some situations. Another possibility is a cylinder.
For a really high quality sky you can make a sky lighting simulation, setting the sphere colors depending on the time (=> sun position!) and direction, and add some clouds as 3D objects between the sky sphere and the view position.