Snow Accumulation and Generation Final

Finally Done!! Thanks to Patrick and Karl.

Video:

Code and Paper Link: https://github.com/DemiChen/SnowAccumulation

Final Presentation

Snow accumulation and ge neration from juicedemi

Snow Accumulation Progress

I spent my weekend finding how to render to texture.
I encountered several problems, which are mostly due to my innocence.I found that I had never truly learnt about OpenGL before. Programming in OpenGL is really hard for me. There are so many features in the OpenGL. Often, to successfully render an image on the screen needs a lot of call for APIs. I was kind of lost  and often forgot something, then I spent a lot of time finding those bugs. One problem was about the indices type. Meshes are deformed. Because the obj load source code use int type for indices. However, in OpenGL, there are only GL_UNSIGNED_BYTE and GL_UNSIGNED_SHORT.

Let me talk about what I have learnt this week. I learnt how to use the framebuffer of OpenGL. There are many attachments for a frame buffer, like color and depth. We could render both to buffers or texture objects. In my project, I use rendering to texture. In the glsl, we could directly write to the buffers, by specifying the out variables in shaders, also don't forget to give the out variables locations, so that the OpenGL know which variable write to which buffer.

Now I have a new problem. I don't know how to output two depth maps from just one shader. I input two transformation matrices and pass two position vecs into fragment shader .In the fragment shader, write them into output textures. Unfortunately,  this method doesn't work..T T..

Falling Snow

Until now, I didn't get much progress.  I only get the snow falling works partly.

The theory is simple. First generate random positions for snowflakes as well as scales. And then according to the depth of snow, calculate the alpha value of color. Essentially, a snowflake is just simple squares. What makes them look like snowflakes is the texture attached to the squares.

Although the method is simple, I encountered problems in the implementation. The biggest obstacle is that I am  a beginner for three.js library. Due to the fact that the three.js library is not complete yet, some tutorials codes even cannot run on my machine. I have to spend much time to fix it. That is exact the reason my snowflakes are still squares. I don't know why I could attach texture to the squares, although I did exactly as the tutorial. For the animation, as usual, I do it in the vertex shader.