Sample showing transform feedback input to instanced draw

tsherif commented 7 years ago

@shrekshao @kenrussell Done :)

kenrussell commented 7 years ago

Very nice. Skimming through this, it looks good, but @shrekshao should fully review and merge it.

shrekshao commented 7 years ago

Hopefully by the end of this week. At the End of semester and whole student career....

On May 1, 2017 7:24 PM, "Ken Russell" notifications@github.com wrote:

Very nice. Skimming through this, it looks good, but @shrekshao https://github.com/shrekshao should fully review and merge it.

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tsherif commented 7 years ago

Haha, no worries :) Good luck, @shrekshao!

kenrussell commented 7 years ago

Good luck @shrekshao !

shrekshao commented 7 years ago

@tsherif @kenrussell I have a different understanding on how the combining of transform feedback and draw instance should work. Tarek's sample basically applies transform feedback to the geometry vertices buffer (trianglePositions). There are two problems:

The buffer itself is small (6 floats), which is not very necessary to use transform feedback
The purpose of this operation is like procedural generation of the geometry which can be useful when we have a complex geometry and needed some dynamic effects (e.g. dynamic vertex displacement). But this has weak relation with draw instance.

So I made some modification based on Tarek's code. It is now a simple agent aimlessly wandering simulation and draw a geometry for each agent instead of rasterize points, which is a better scenario (at least from my point of view) because:

Apply the transform feedback on a large attribute buffer (offset and rotation, the size of which are proportional to the number of instances)
Has a stronger relation with draw instance. Because the geometry of agent can be complex, e.g. a human model when doing crowd simulation.

The new pull request is #149 . Here's a preview:

WebGLSamples / WebGL2Samples

Sample showing transform feedback input to instanced draw #148