Application screenshot: http://i.imgur.com/0uVKZiL.png
Source file: http://pastie.org/private/rcgm6o7qso8y0vz8nfjn0w
My application draws curves and I would like to be able to zoom in and out. When I apply a scale and translate transformation, the mapCanvasImage.canvas().gfx.transform changes accordingly, but nothing changes on the screen.
I used to have a different render approach (source code) in which the transformation did work, but there I could not get the layer to clear after each paint (results from previous paint iterations were still visible).
Perhaps (or likely) I am doing something fundamentally wrong. :) Any advice?
The Canvas offers nice high-level functions to draw Bézier curves, but is apparently flawed. My current plan is to abandon the Canvas and write my own code to convert Bézier curves to line segments. This is really easy and gives the added benefit of using less CPU power, since the Canvas is not hardware accelerated.
Related
I know that if I rotate an object, which extends javafx.scene.shape.Shape, I can transform it into 3D space, even though it was primarily designed to be in 2D (at least as far as I know).
Let's say I have a 3D scene (perspective camera and depth buffer are used), where various MeshViews occur. Some are used for areas, others for lines. In both cases those shapes must be triangulated in order to draw them with a TriangleMesh, which is often nontrivial.
Now when I change the drawing of these lines to use the Polyline class, the performance collapse is horrible and there a strange artefacts. I thought I could benefit from the fact, that a polyline has less vertices and the developer doesn't have to triangulate programmatically.
Is it discouraged to use shapes extending javafx.scene.shape.Shape within 3D space? How're they drawn internally?
If the question is "should I use 2D Shape objects in 3D space?" in JavaFX then the answer is No because you will get all terrible performance that you are seeing. However it sounds like you are trying to make up for JavaFX's lack of a 3D PolyLine object using 2D objects and rotating them in 3D space. If that is true, instead use the free open-source F(X)yz library:
http://birdasaur.github.io/FXyz/
For example the PolyLine3D class which allows you to simply specify a list of Point3Ds and it will connect them for you:
/src/org/fxyz/shapes/composites/PolyLine3D.java
and you can see example code on how to use it in the test directory:
/src/org/fxyz/tests/PolyLine3DTest.java
Basically, I'm looking for something like this awesome research project: Gmap, which was referenced in this related SO question.
It's a rather novel data visualization that combines a network graph with an imaginary set of regions that looks like a map. Basically, the map-ification helps humans comprehend the enormous data set better.
Cool, huh? GMap doesn't appear to be open source, though I plan to contact the authors.
I already know how to create a network graph with a force-directed layout (currently using Prefuse/Flare), so an answer could be a way to layer a mapping algorithm on top of an existing graph. I'm also not concerned about the client-side at all right now - this would be a backend process, and I am flexible about technology stack and data output at this stage.
There's also this paper that describes the algorithm backing GMap. If you have heard of Voronoi diagrams (which rock, but make my head hurt), this paper is for you. I quit after Calc 1, though, so I'm hoping to avoid remembering what sigmas and epsilons are.
As a start, could you do a simple closest point sort of an algorithm? So it looks something like this: You have your force directed layout and have computed some sort of bounding box. Now you want to render it. Adjust your bounding box to line up to the origin and then as you calculate the color of each pixel, find it's closest point. This should generate some semblance of regions and should be quite simple to try out. Of course, it isn't going to be as pretty as GMap, but maybe a start? The runtime would be awful, but... I don't know about you but computing boundary lines directly sounds a lot harder to me.
First off, I am not after any instructions on logic for collision detection; I get it.
What I am trying to work out is the least complicated way to do this with Pygame using Sprites & Rects. I want to be able to check collisions for the Player against ground, walls & slopes. In theory it is quite straight forward, but I'm having difficulty because it seems like you cannot do this with one Rect.
One Rect is simple enough to get you collisions in the X plane against walls. The same Rect could be used also be used in the Y plane against solids, but not with slopes - since with the collision routines in Pygame it checks the whole Rect (or mask), rather than perhaps just the bottom middle of the Rect. It seems in addition you need to have a number of "sprites" to check collisions with, that are 1x1 pixel in various places around the Player.
What's the easiest way to do this, without having a bunch of 3, 4, or more separate "collision pixels" to check against slopes?
Geoff
It sound to me like you want pixel perfect collision detection. Here you can find a premade function that seems to me to be what you want/need.
You could use pygame.mask, which provides pixel perfect collision detection in C:
http://www.pygame.org/docs/ref/mask.html
When you use Graphics object to draw very large shape(that does not fit in 10000x10000 pixels) stroke width may become much wider than value specified in lineStyle function.
What are the workarounds to overcome this?
For now I have only two options:
1. When drawing line you can split it into several lines. However this trick does work only for drawing lines, polylines and polygons. There is no way to apply this to drawing circles and ellipses. Well, we can approximate circles via bezier curves, but this approach seems to be very inefficient.
2. Perform manual cliping. But this require manual implementation of different cliping techiniques, and I think ActionScript does not suit well for this sort of task. And again there is need to approximate visible parts of large circles.
Out of interest are you using the scrollRect as this will prevent anything not in the view port from being drawn and will hopefully help you solve this.
Andrew
I am IT student and I have to make a project in VB6, I was thinking to make a 3D Software Renderer but I don't really know where to start, I found a few tutorials but I want something that goes in depth with the maths and algorithms, I will like something that shows how to make 3D transformations, Camera, lights, shading ...
It does not matter the programing language used, I just need some resources that shows me exactly how to make this.
So I just want to know where to find some resources, or you can show me some source code and tell me where to start from.
Or if any of you have a better idea for a VB6 project.
Thanks.
I disagree with the previous posts, a 3D renderer is actually pretty simple. A high-quality 3D renderer is hard however.
Get a bunch of 3D data, triangles are simplest.
Learn about homogenous coordinates and the great 4x4 matrix for transforms.
Define a camera by a position and a rotation (expressed in the 4x4 matrix).
Transform your 3D geometry by this camera.
Perform the perspective divide and scale to your window. This converts your 3D data to 2D.
Render the data as 2D.
Now you're going to lose out on a depth buffer, so stick to wireframes in the beginning. :-)
Don't listen to these nay-sayers, go out and have some fun!
Many years ago I made a shaded triangle renderer that used library calls to draw the triangles. It's a rather naive approach but you would be able to achieve the same result using VB6. I got all the maths & techniques from "Computer Graphics principles and practice" by Foley et al. Some parts are out of date now but I think you'd find it very helpful for this project and it can be bought 2nd hand at reasonable prices from Amazon for example.
One simple approach could be:
Read model file as triangles
Transform each triangle using matrices to account for camera position
Project triangle points onto 2D
Draw 2D triangle (probably using GDI)
This covers wireframe viewing. To extend this to hidden surface removal you need to work out which triangles are in front. Two possible ways:
Z-order sorting the triangles and drawing the ones furthest from the camera first. This is simple but inefficient if there are a lot of triangles and can give overlapping triangle effects when the order is not quite correct. You also have to decide how to sort the triangles - e..g by centroid, by extents...
Using a software depth buffer. This will give better results but is more work to implement. You will have to write your own triangle drawing code so cannot rely on GDI. See bresenham's line algorithm and related algorithms for doing filled triangles for how to do this.
After this you'd also need some kind of shading based on lighting. The calculations are covered in Computer Graphics principles and practice. For simple shading you can stick with drawing triangles using gdi , but if you want to do gouraud or phong shading the colour values vary across a triangle. One way around this is to sub-divide the triangle into smaller triangles, but this is inefficient and won't give very nice looking results. Better would be to draw the triangles yourself as required above for the software depth buffer.
A good extension would be to support primitives other than triangles. Basic approach would be to split primitives into triangles as you read them.
Good luck - could be an interesting project.
VB6 is not the best suited language to do maths and 3D graphics, and given that you have no previous knowledge about the subject either, I would recommend you to choose something different (and easier).
As it's Visual Basic, you could try something more form-oriented, that is the original intent of the language.
There is the 3D engine list which lists three engine in pure basic (an oxymoron) + Source code and of them one is in Visual Basic (Dex3D)
DeX3D is an open source 3D engine
coded entirely in Visual Basic from
Jerry Chen ( -onlyuser#hotmail.com ).
Gouraud shading
Transparency
Fogging
Omni and spot lights
Hierarchical meshes
Support for 3D Studio files
Particle systems
Bezier curve segments
2.5 D text
Visual Basic source
More information, screenshots and the
source can be found on the Dex3D
Homepage. (<= Dead Link)
EGL25 by Erkan Sanli is a fast open source VB 6 renderer that can render, rotate, animate, etc. complex solid shapes made of thousands of polygons. Just Windows API calls – no DirectX, no OpenGL.
VBMigration.com chose EGL25 as a high-quality open-source VB6 project to demonstrate their VB6 to VB.Net upgrade tool.
A 3D software renderer as a whole project is fairly complex if you've never done it before. I would suggest something smaller - like just doing the 3D portion and using lines to do the rendering OR just write a shaded triangle renderer (which is the underpinnings of 3D renderers anyway).
Something a little simpler rather than trying to write a full-blown 3D software renderer on the first go - especially in VB.
A software renderer is a very difficult project and the language VB6 is not indicated at all ( for a task like this c++ is the way.. ), anyway I can suggest you some great books I used:
Shaders: http://wiki.gamedev.net/index.php/D3DBook:Introduction_%28Volume%29
Math: 3D Math Primer for Graphics and Game Development
There are other 2 books. Even if they are for VB.NET you can find some useful code:
.NET Game Programming with DirectX 9.0
Beginning .NET Game Programming in VB .NET
I think you can take two ways either go the Direct X way and use DirectX 8 that has VB 5-6 support. I found a page http://www.gamedev.net/reference/articles/article1308.asp
You can always write a engine group up but by doing so you will need some basic linear algebra like Frank Krueger suggests.