Programming 3d Games in Java Ask Question. Asked 10 years, 3 months ago. Active 10 years, 3 months ago. Viewed 4k times. Can you guys recomend me some books that help me understad 3d game development in Java better? Aly Aly 1 1 gold badge 2 2 silver badges 3 3 bronze badges. Add a comment. Active Oldest Votes. You can use OGRE wrapper for java! Luca Davanzo Luca Davanzo Sign up or log in Sign up using Google. Thank again.
You're welcome! No, OpenGL will be much faster - it uses a lot of clever optimizations and also benefits from graphic card. This sample is purely software, so it is at a disadvantage. Only until z-buffer came into play - after that, it will be impossible to determine z-coordinate from g2. Is there any clever way to reorganize the shapes in the render array, so they come out in order?
Could I sort polygons by their maximum Z value? I don't think so. Consider the case of two intersecting triangles - in some pixels triangle 1 will be above, in other triangle 2 will be above. So there will be no strictly defined order. Again, not for all cases - imagine configuration with 3 shapes A,B,C , where A partially overlays B and is partially overlaid by C, B in turn overlays C, and lastly C is partially obscured by B and is above A.
Again, no strict ordering. Oh, ok. Thought I could get away with using g2. Welp, time to rewrite my Renderable interface. Could I implement this using polygons that take any number of inputs, as opposed to just triangles? You just need to create rasterization method for your polygons.
But as far as I know, this will involve splitting polygon into several triangles and then rasterizing those - so you're back at square one. That's the basic reasoning behind the fact that video cards only work with triangles - all polygons can be viewed as a group of adjacent triangles, so it's much simpler to unify all interfaces and view the whole world as lots of triangles.
Why do you need to use barycentric coordinates when determining if a pixel lies inside the triangle's area? Isn't it possible to just use the pixel coordinates and paint the triangle accordingly?
It is the simplest method, easier to understand and implement - so I decided to use it in this tutorial. There are several others, but they require vertex sorting and complex logic with many corner cases. Is it possible to use the barycentric coordinate system in this tutorial to get texture coordinates on an image? Yes, I suppose. You will need to assign texture coordinates to vertices, and then interpolate using barycentric coordinates to get texture coordinates inside the triangle.
I have been able to understand and create my own 3D rendering engine using the great tutorial you have provided and a lot of other documents that explain all of the mathematics beind it. With all of this said, I still have a few questions. My major one right now is if it is possible to use the zbuffer with only two baricentric coordinates. Any insight on a possible solution would be very helpful.
Unless you check the third coordinate as well, you may get points outside triangle area b3 may be negative,for example. If you want to improve the performance, it would be much better to remove barycentric computations completely and use better rasterization algorithms.
I figured that it is possible to substitute the third baricentric coordinate by subtracting the sum of the first and second baricentric coordinate from 1 Not too long after I posted the question actually This way you can successfully calculate the correct distance for the zbuffer.
It is even possible to use the baricentric coordinates directly as texture coordinates as well. Now that you mention it, do you know any better algorithms for rasterizing triangles I might be able to look into? That's harder. If you need to go that way, you will probably still need some form of barycentric coordinates. I am curious to see how fast my modified 3D rendering program would run using the GPU to render the objects. Is there a way to implement a camera position into this program or is it purely a fixed view system?
Of course. In fact, rotation examples in the article do exactly that - you can think of rotating object in front of fixed camera as of rotating camera around a fixed object. As far as I know, in real 3D-engines camera positions are also implemented this way - camera is always positioned at 0,0,0 and rendered scene is transformed into that "camera space". Instead of working in pixel coordinates, you could use homogenous coordinates x and y axis is between -1 and 1.
From there, you can use a projection, view and model matrix to control the vertex positions on the screen. The first rotation matrix in the article achieves just that. Or maybe you are looking for something else? I mean, I can only rotate it in 2 ways. How can I rotate it in the 3rd way? Current examples only show heading and pitch transformations. I work with BlueJ and when I try to compile the triangle-class from the 2nd code example it says, that it cannot find the class Color.
Could you help me out with this? That's an easy fix - you probably placed that into a separate file, so it can't find the required imports. Add "import java. I have more or less created my own 3D engine in Java and I'm using scan line rasterisation and refreshing at 60Hz but the problem I am encountering is when painting with the graphics object it cannot paint enough between frames and gives me a semi complete surface with artifacting near the bottom. And when I try drawing the surface on a bufferedimage and render that with a graphics object I get a refresh rate of 60Hz.
Any advice on what I should do? Change the rasterisation method etc. Thank you. Edit: I have also overridden the paint method to try and reduce latency without much success. You are looking for double-buffering. Just call. Essentially, it is almost the same as your solution with buffered image - all drawing commands are first output to temporary image, and only after the drawing is complete that image is drawn on actual screen.
Which java version are you using? Seems it fails on lambda expressions, which were introduced in Java 8. For older java versions, you can rewrite those lines as follows: headingSlider. Hello Rogach - I am really impressed with how simple this demo is.
However, it only shows an affine projection. How difficult would it be to make it a fully 4x4 matrix for perspective projection? I am trying to build a simple cube viewer that I can control the FoV. But not much point unless fully perspective. Can you help? You probably don't need 4x4 matrix for perspective projection - you can just divide by Z coordinate but just be careful with negative z values.
But camera control will feel weird in that case, since in current implementation camera is strictly situated at 0,0,0 and there is no way to handle translations in 3x3 matrix. Expanding to 4x4 matrix should not be hard - just add W coordinate to Vertex, replace Matrix3 class with Matrix4 with appropriate changes , add a [0,0,0,1] row and column to heading, roll and pitch transforms, and add a pan transform somewhere.
Here is some code that is able to convert the original affine screen coordinates to perspective projection coordinates. Don't worry about the extra array lists, those are just for my own organization purposes. This looks more like fish-eye projection, not perspective projection. For example, consider several objects with equal Z coordinate. Under this projection, object close to the center will get one value of R, but for object far away from the center but still at the same Z R will be greater 2x, for example.
Thus objects away from the center will be smaller since you divide by R. Yes, it does fish-eye the image, but technically it is mathematically correct perspective projection. For it to look like proper perspective projections in computer graphics, all you have to do is divide by the Z value, not the radial distance to the camera. Saw your comment and was wondering if you were able to do this with a positionable camera. Ok - I'll give it a go. What I like about your implementation is that it is almost entirely raw java - you are not using the Java3D API, which already has its own camera class and so on.
The way you have done it means you need to understand every aspect to get it to work. If you already have an example with a 4x4 matrix that would be useful However, I do not really have a perspective view just distorted isometric. Still need to do some maths on the w value ie scale z or w? Any ideas? I changed your tetrahedron to a cube.
I don't think you can achieve perspective projection using only a matrix - basically, you need to divide X and Y by Z coordinate, and that's not possible to do via matrix multiplication on the vector.
For example, OpenGL's perspective projection matrix is only needed for clipping - actual perspective projection happens manually after all the matrices.
The actual magic happens in lines fov angle to scaling computation and lines division by Z. You'll probably want to rewrite the GUI to see the effects better - you now need 6 sliders: 3 for camera XYZ position and 3 for camera rotation. Any ideas how to adjust the distance from the nominal camera position whilst adjusting the FoV? All of the variables ending in DistX or DistY are calculated so that the program only checks for collisions at the places where collisions could possibly occur. This will be calculated later.
After that is done we need to figure out a few of the other variables based on the one we already calculated. Once that is done it is time to figure out where the ray collides with a wall. To do this the program goes through a loop where it checks if the ray has come into contact with a wall, and if not moves to the next possible collision point before checking again. Now that we know where the ray hits a wall we can start figuring out how the wall should look in the vertical stripe we are currently on.
To do this we first calculate the distance to the wall, and then use that distance to figure out how tall the wall should appear in the vertical strip. We then translate that height to a start and finish in terms of the pixels on the screen. The code looks like this:. After that is calculated it is time to begin figuring out what pixels from the texture of the wall will actually appear to the user. For this we first must figure out what texture is associated with the wall we just hit and then figure out the x-coordinate on the texture of the pixels that will appear to the user.
The x-coordinate is calculated by taking the exact position of where the wall was hit on the 2D map and subtracting the integer value, leaving only the decimal. This decimal wallX is then multiplied by the size of the texture of the wall to get the exact x-coordinate on the wall of the pixels we wish to draw. Once we know that the only thing left to do is calculate the y-coordinates of the pixels on the texture and draw them on the screen. To do this we loop through all of the pixels on the screen in the vertical strip we are doing calculations for and calculate the the exact y-coordinate of the pixel on the texture.
Using this the program then writes the data from the pixel on the texture into the array of pixels on the screen. The program also makes horizontal walls darker than vertical walls here to give a basic lighting effect. And the class is done. Now all we have to do is add a few lines of code in the Game class to get the screen working. With the variables at the top add this:. Question 5 weeks ago. Question 7 months ago on Step 1. Question 11 months ago. Question 1 year ago. Does anyone have a hard maze map that I could try for this program?
I'm not very good at making mazes, or maps in general. Thank you! Answer 11 months ago. Hi everyone, I would be ever so grateful if someone could explain how I could draw an image over the pre-existing display from the screen.
Great tutorial! So glad I stumbled upon it. Only issue I had was same thing a couple people on here did. Textures for wall displayed as black images only. Realized when I down loaded images, my browser saved them as a different format, even though it said.
Loaded them into gimp , then exported as. Also as my pic shows, added a 5th texture to serve as portal. Again great tutorial. Hope you add more. Tip 1 year ago. Reply 1 year ago. Question 3 years ago. Answer 3 years ago.
Then stand up. Now bend your knees a little Now, using your leg muscles, push down with both feet. Your entire body should have briefly lifted off the ground. That's how to add jumping to this program! Answer 1 year ago.
Change 'public boolean left, right, forward, back;' to 'public boolean left, right, forward, back, stepLeft, stepRight;' Add 'if key.
Add 'if key. For this class the imports will be: import java. The start and stop methods are simple and used to make sure the program safely starts and ends. The imports for the class are: import java. File; import java. IOException; import javax. KeyListener; Many variables are needed to keep track of the camera's position and what it can see. In the Game class' run method add the following line of code where it is shown here Add this: camera. To work, the class needs the following imports: import java.
ArrayList; import java. SIZE - texX - 1; The x-coordinate is calculated by taking the exact position of where the wall was hit on the 2D map and subtracting the integer value, leaving only the decimal.
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