问题
How can I add a glowing effect to a line that I draw? I'm using OpenGL for Linux.
回答1:
You can implement the radial blur effect described on Nehe Lesson 36. The main idea is to render the drawing to a texture, and do that N times with a small offset after each render, until the drawing is ready to be copied to the framebuffer.
I've written a small demo that uses Qt and OpenGL. You can see the original drawing (without the blur) below:
The next image shows the drawing with the blur effect turned on:
I know it's not much, but it's a start.
回答2:
I too once hoped there was a very simple solution to this, but unfortunately it is a little complicated, at least for a beginner.
The way glowing effects are implemented today, regardless of API (D3D,OpenGL) is with pixel/fragment-shaders. It usually involves multiple render passes where you render your scene, then render a pass where only "glowing objects" are visible, then you apply a bloom pixelshader and compose them together.
See the link provided by @Valmond for details
Edit:
It should be added that this can be achieved with deferred rendering, where normals, positions and other information like a "glow flag" is rendered to a texture, i.e. stored in different components of the texture. Then a shader will read from the textures and do lightning computations and post-processing effects in a single pass since all data it needs is available from that rendered texture.
回答3:
Check this out : http://developer.download.nvidia.com/books/HTML/gpugems/gpugems_ch21.html
It explains easily how to make glow effects.
回答4:
Without using shaders, you might also try rendering to texture and doing a radial blur. As a starting point check out NeHe-Tutorials.
来源：https://stackoverflow.com/questions/8293839/how-to-add-glowing-effect-to-a-line-for-opengl