I'm having a hard time finding the equivalent of the very basic OpenGL functionality glPushMatrix and glPopMatrix in LibGDX.
I have rendered my scene and I would like to render an overlay on top of the scene but I would like to do it in screen coordinates so I want to push the modelview matrix and load identity.
In essence I would like to perform the equivalent of:
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glLoadIdentity();
... stuff ...
glPopMatrix();
But for the life of me, I cannot find a single mention of push or pop in the LibGDX documentation nor in the parts of source code that I have looked at.
Am I missing something? Is there some other preferred way of achieving this?
Edit:
What I want to achieve is a fade to black while I load the next level and then fade in. I do this by rendering a black rectangle over the display with alpha. None of that is a problem, I just want to have a fixed, known coordinate system independent of the current world transform to render this rectangle in.
Those methods are part of the fixed render pipe of OpenGL ES 1. Support for OpenGL ES 1 has been removed since libGDX version 1.0.0. Only the programmable render pipe op OpenGL ES 2 and up is supported. If you really want to use such old methods then you could use an older version of libGDX.
The question "how to render a HUD overlay?" is too broad to explain here. But for basic methods (like rendering a HUD overlay) libGDX abstracts away the need of using any gl methods at all. You might want to have a look at the wiki, which includes some basic examples. And follow a tutorial (although tutorials tend to get outdated of time, so be aware of that).
But assuming you are using SpriteBatch, then use batch.setProjectionMatrix()
Related
I am trying to make a simple game using OpenGL. I have already modeled 3D scene. Now I want to add some fog to make it look like in horror. I have used this code below
gl.glEnable(GL2.GL_FOG);
gl.glFogi(GL2.GL_FOG_MODE,GL2.GL_LINEAR);
gl.glFogi(GL2.GL_FOG_START,(int)1);
gl.glFogi(GL2.GL_FOG_END,(int)5);
However that just creates a static fog with some random coordinates. How to make It dependent on the camera movement? So the player will only see clearly on the set distance?
You can find the definition of glFog (and all the other OpenGL commands, even the classic ones) at www.opengl.org. Fog is always calculated according to the distance from the eye / camera / viewpoint coordinates, so you don't need to do anything special.
Be warned that glFog is part of the old classic OpenGL API and may not work reliably on modern 3D systems.
I'm creating a 2d game using the Java version of Box2d.
I know that the engine is generally paired with a separate library to handle animation, but I'm looking for something simple, with a more rustic feel, so I'm considering handling the animation from scratch.
The animation I am trying to create is something for the collision of two objects.
I'm using openGl to handle the graphics, and I pretty much have everything set up with the fps and rendering, it's just a matter of tweaking the frames to make it look smooth.
I tried bliting images of some things that I drew myself and it looked atrocious. I think the main problem is that the animation frame images are not linked to the physics forces and so they don't blend well.
What I want to try next is a sort 'spark effect' using a small number of pixels that sort of resemble 'dust' exploding off of the colliding images. If you've ever played dxball, you may recall a similar effect when the ball collided with the paddle at high speed.
As you can see in the above image, the principles are fairly simple. I figure by creating a set of small bodies with fixtures, I can use the box2d engine to produce this effect. I already have code that grabs the point of collision for all bodies, and am familiar enough with parabolic functions that I pretty sure I can create the force direction.
I'm just not sure if there is a better way of doing this, or how to apply a polynomial function to a body like in the image.
Does anybody know how to achieve this functionality with box2d? Any built in methods or documentation that would be helpful?
As a point of reference, the following snippet of code demonstrates the drawing of a small, red box on all of the collision points.
for(Vec2 point : listener.worldmanifold.points){
glPushMatrix();
newpos = point.mul(30);
glTranslatef(newpos.x, newpos.y, 0);
glColor3f(1,0,0);
glRectf(-2, -2, 2, 2);
glPopMatrix();
}
Can graphics rendered using OpenGL work with graphics rendered not using OpenGL?
I am starting to learn OpenGL, but I am still shy when it comes to actually coding everything in OpenGL, I feel more comfortable drawing them out with JPanel or Canvas. I'm assuming that it wouldn't cause much issue code wise, but displaying it all at the same time could cause issues? Or am I stuck with one or the other?
Integrating OpenGL graphics with another non-OpenGL image or rendering boils down to compositing images. You can take a 2D image and load it as a texture in OpenGL, such that you can then use that texture to paint a surface in OpenGL, or as is suggested by your question, paint a background. Alternatively, you can use framebuffers in OpenGL to render an OpenGL scene to a texture, when can then be converted to a 2D bitmap and combined with another image.
There are limitations to this approach of course. Once an OpenGL scene has been moved to a 2D image, generally you lose all depth (it's possible to preserve depth in an additional channel in the image if you want to do that, but it would involve additional work).
In addition, since presumably you want one image to not simply overwrite the other, you're going to have to include an alpha (transparency) channel in one of your images, so that when you combine them, areas which haven't been drawn will end up showing the underlying image.
However, I would suggest you undertake the effort to simply find one rendering API that serves all your needs. The extra work you do to combine rendering output from two APIs is probably going to be wasted effort in the long run. It's one thing to embed an OpenGL control into an enclosing application that renders many of it's controls using a more conventional API like AWT. On the other hand, it's highly unusual to try to composite output from both OpenGL and another rendering API into the same output area.
Perhaps if you could provide a more concrete example of what kinds of rendering you're talking about, people could offer more helpful advice.
You're stuck with one or the other. You can't put them together.
I am developing a 3D game using the Libgx 3D api. Now i want to add some environment (not the Libgdx Environment, but a real environment), like the sky or some background. I have heard about the so called skybox, and i understood, more or less, how it works.
This "skybox" is a Box arround your Gameworld. So you are inside this box. You add a Texture to all 6 faces at the inside of this box. Now you set your camera to the center of this box, but with the right view direction, and start the rendering, so you have always the same distance to the faces, but you can rotate arround at look at other faces. Then you set your camera where you really are in the world and render all the models, objects, whatever. Did i understand that right?
I could not find a tutorial on how to do that with libgdx. So my question is: How do i create a "skybox" in libgdx, how do i add my Textures to it and how do i render it as background/environment? Or are there other, maybe easier possibilities?
You can use big sphere which is textured inside around your world. If use blender, just create sphere object and unwrap this mesh. Then flip normals to see texture inside the sphere.
Another way is to create cubemap as you described above. I have made a class which works with cubemap. Just follow this link: LibGDX 0.9.9 - Apply cubemap in environment
I need a suggestion/idea how to create a 3D Tag Cloud in Java (Swing)
(exactly like shown here: http://www.adesblog.com/2008/08/27/wp-cumulus-plugin/)
, could you help, please?
I'd go either with Swing and Java2D or OpenGL (JOGL).
I used OpenGL few times and drawing text is easy using JOGL's extenstions (TextRenderer).
If you choose Swing, than the hard part will be implementation of a 3D transformation. You'd have to write some sort of particle system. The particles would have to reside on a 3D sphere. You personally would be responsible of doing any 3D transformation, but using orthogonal projection that would be trivial. So it's a nice exercise - what You need is here: Wiki's spherical coord sys and here 3d to 2d projection.
After You made all of the transformation only drawing is left. And Java2D and Swing have very convenient API for this. It would boil down to pick font size and draw text at given coordinates. Custom JPanel with overriden paintComponent method would be enough to start and finish.
As for the second choice the hardest part is OpenGL API itself. It's procedural so if You're familiar mostly with Java You would have hard time using non-OO stuff. It can get used to and, to be honest, can be quite rewarding since You can do a lot with it. If you picked OpenGL than you would get all the 3D transformations for free, but still have to transform from spherical coordinate system to cartesian by yourself (first wiki article still helpful). After that it's just a matter of using some text drawing class, such as TextRenderer that comes with JOGL distribution.
So OpenGL helps You with view projection calculations and is hardware accelerated. The Java2D would require more math to use, but in my opinion, this approach seems a bit easier. Oh, and by the way - the Java2D tries to use any graphic acceleration there is (OpenGL or DirectDraw) internally. So You are shielded from certain low-level problems.
For both options You need also to bind mouse coordinates s to rotational speed of sphere. Whether it's Java2D or OpenGL the code will look very similar. Just map mouse coordinates related to the center of panel to some speed vector. At the drawing time You could use the vector to rotate the sphere accordingly.
And one more thing: if You would want to try OpenGL I'd recommend: Processing language created on MIT especially for rich graphic applets. Their 3D API, not so coincidentally, is almost the same as OpenGL, but without much of the cruft. So if You want the quickest prototype that's the best bet. Consult this discussion thread for actual example. Note: Processing is written in Java.
That's not really 3D. There are no perspective transformations or mapping the text on some 3D shape (such as, say, a sphere). What you have is a bunch of strings where each string has an associated depth (or Z order). Strings "closer" to you are painted with a stronger shade of gray and larger font size.
The motion of each string as you move the mouse is indeed a 3D shape which looks like a slanted circle around a fixed center - with the slant depending on where the mouse cursor is. That's simple math - if you figure it for one string, you figure it out for all. And then the last piece would be to scatter the strings so that they don't overlap too much, and give each one the initial weight based on their frequency.
That's what most of the code is doing. So you need to either do the math, or translate the ActionScript to Java2D blindly. And no, there is no need for JOGL.
Why don't you just download the source code, and have a look? Even if you can't write PHP, it should still be possible to read it and figure out how the algorithm works.