问题
Currently, I am working on a OpenGL project and here is the screenshoot what I did
The question is, I want to add texts(degrees) to compass and want to do that with pure OpenGl methods. I found TextRenderer class however, couldn't manage to download it and use it. How to use TextRenderer class in my Java project? If there is any other way of adding text besides TextRenderer, would love to hear it.
My second and most important question is about merging swing/awt methods with OpenGL and using multiple objects. I wrote the program with only using one GL2 object and worked perfectly, is it sensible to use multiple openGL objects on the same frame? Furthermore, using swing methods and openGL methods together is a good idea?
回答1:
I want to add texts(degrees) to compass and want to do that with pure OpenGl methods.
Unless you can live with not very pleasantly looking center stroke fonts, you have no choice but to use help from some other library or API.
Theoretically OpenGL can collaborate with OpenVG, but so far overall support for OpenVG is very poor, and OpenGL interoperability even worse. But say you had a proper working OpenVG – OpenGL interoperability working, then OpenVG was the way to go.
Practically you have to something different. A very fruitful approach is to use a font renderer library (like FreeType) together with some layout engine (like Pango) to produce an outline stroke list of the text to be rendered, which in turn can be either rendered directly using some extension by NVidia (http://www.opengl.org/registry/specs/NV/path_rendering.txt available only on the most recent NVidia GPUs) or manually tesselated into triangles, either on the CPU or by a combination of GPU Geometry and Tesselation Shaders. A huge drawback of drawing glyphs as tesselated filled outlines with OpenGL primitives is, that they will look very dirty (due to aliasing) if the used framebuffer doesn't have a multisample format (full screen antialiasing)
The next best thing is rendering the text to an image and copying that to the GPU and overlay that over the scene by rendering a textured quad. You should apply all text transformations already when rendering the quad, so that the font hinting system can make the proper adjustments on the transformed glyphs before rasterizing them.
Another approach is using texture mapped fonts. I implemented two TMF engines myself so far, but personally I advise against using this approach these days, as TMFs are resource hogs. A 200kiB TTF font can blow up to several megabytes of texture data. Maybe one day I or somebody else implements a TrueType or OpenType rendering engine with OpenCL, CUDA or Compute Shader, but until then rendering text with OpenGL is dirty business.
It boils down to
- Crisp Look
- Memory Efficient
- Computationally Efficient
→ choose 2
回答2:
After doing little research, I ve figured out how to install it and use it correctly.
Firstly, go to that web site and download suitable version of jogl for your os in case you dont have any library: http://jogamp.org/deployment/autobuilds/master/jogl-b1011-2013-06-19_05-41-38/
Then, download that jar file and add it to your user library. http://www.java2s.com/Code/Jar/j/Downloadjogl20jar.htm
That file contains the TextRenderer class.
If you dont know how to make one, use that link: http://riccardotramma.com/2011/04/setup-eclipse-to-develop-opengl-glut-apps-in-java-cc-on-windows-mac/
Then, follow the instructions: http://download.java.net/media/jogl/jogl-2.x-docs/com/sun/opengl/util/awt/TextRenderer.html
It's very easy to use, I perfectly added numbers to my compass. However, not efficient as far as I can tell.
来源：https://stackoverflow.com/questions/17208441/adding-text-to-screen-with-opengl