September 2017 – Xiaoxu Meng

09/22/2017

The obj file of sponza model has texture coordinates beyond [0,1], it even has negative numbers! When I map it to Gbuffer, the texture2D() just went wrong. So should use vec2 newTextCoord = fract(TextCoord);

Shang gave me a mechanical keyboard, feeling so cool with it!

A 99 line global illumination: (path tracing) http://www.kevinbeason.com/smallpt/

Tasks:

Others:

Bug for log polar transformation for meshes:
- 1. Is it caused by input quads?
  - I guess no. As https://www.opengl.org/discussion_boards/showthread.php/175665-Geometry-shader-to-handle-quads said, those types (quads) are all tessellated by the driver to triangles before being passed to the geometry shader. Each quad would be split into two triangles and these would be processed separately by the geometry shader.

Research:

Fixed depth error. Should initialize depth buffer after obj load
Fixed drawing triangles for the cut line:
- I wrongly set the “layout (triangle_strip, max_vertices = 3) out”, if max_vertices = 3, only one triangle will be outputted!
Should use vertex, tess, geom, frag shaders together now! Let recall the whole pipeline…https://www.khronos.org/opengl/wiki/Rendering_Pipeline_Overview
(09/08 added) I met an error for tessellation:
- Correct: https://www.dropbox.com/s/99cp7kk1ja0nbg6/correct.png?dl=0
- Mine: https://www.dropbox.com/s/4o7h3u4fir2j8oc/wrong.png?dl=0
- The reason is: I did coordinate transformation in vertex shader (before tessellation). If coordinate transformation happens before tessellation, the gl_TessCoord would be affected by the transformation.
- Should do: do nothing in vertex shader and do coordinate transformation after the last step in tessellation eval shader.
Use tessellation CTRL shader to determine the level of tessellation:
- how to determine the level dynamically? Can do this
- Ensure that the shared edge(s) between the patches use the same level of tessellation
Use tessellation eval shader to calculate the area of the triangle.
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How to dynamically solve the problem of tessellation?
Central Triangle??

Others:

…悲剧就是将美好的东西毁灭给人看…

Problem:

Could load texture correctly when rendering to framebuffer. However, when framebuffer is used, only left down corner of the texture is displayed.

Solve:

I loaded a model with some texture initialization before initiating framebuffer. And the model affected the initialization of framebuffer;

Should initialize framebuffer before loading the model.

Task for tomorrow:

Try every simple mesh in the object separately.

Assignment1: KNN

Install BallTree Library: sudo apt-get install python-sklearn
list.append(), add new item to the end.
numpy.arange(), sort
numpy.reshape(), the same with reshape() in matlab
numpy.median(numpy.array(outs))????
defaultDict.get(), https://stackoverflow.com/questions/11041405/why-dict-getkey-instead-of-dictkey
ballTree.query(X, k == k_in), http://scikit-learn.org/stable/modules/generated/sklearn.neighbors.BallTree.html

BallTree: http://blog.csdn.net/pipisorry/article/details/53156836

Find large model
1. Can load Sponza
2. The loading library is not complete. The .mtl cannot be fully loaded. But the rendering time can achieve >28ms
Color:
1. Patney: people can easily find difference if color is changed.
Use short in to replace float