Tag Archives: GPU

Voxelization using the GPU hardware rasterizer

https://elisabethbell.com/vae6j784jum Last week I started to add a new feature to my tiled deferred renderer: voxelization using the GPU hardware rasterizer. A lot of recent techniques use a voxel grid (global illumination, volumetric effects, etc.) and I really wanted to experiment some of them, especially global illumination.

Tramadol Overnight Mastercard One paper in particular had caught my attention, voxel cone tracing.

https://www.goedkoopvliegen.nl/uncategorized/o76dukf0d1

https://www.mominleggings.com/oonq52i The first step of this technique is voxelization using the hardware rasterizer. There are plenty of resources on this topic:

https://www.worldhumorawards.org/uncategorized/6vp3jhc0qz

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Buy Cheap Tramadol With Mastercard I’m sure there is more on this topic, but there are the main sources of information I used for the first step of my implementation.

https://www.lcclub.co.uk/epo61r3zp

This technique is based on a simple observation. We want to transform vector informations in a (3D) matrix. That’s the job of the rasterizer, except it’s done for a 2D grid. We just need to do some modifications so that it can also work on a 3D grid.

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You can find all of the details in the previous links, but here is a quick overview of the different steps:

  • In the CPU code, compute the voxel grid position, extents, etc. and three view projection matrices, one for each axis. This will allow to project the triangles in the voxel grid space.
  • Draw the whole scene in a small render target. Depth test is deactivated in order to voxelize every triangles. Color write is deactivated as well. Results will be outputted in a structured buffer linked to the pixel shader, and nothing will be written on the texture.  Some minor modifications can be done to store static geometry in the grid, and update only dynamic objects to reduce the runtime calculations.
  • In the geometry shader, for the current triangle, the first step is to find the axis (X, Y or Z) from which the triangle is the most visible. This will ensure that most of it is voxelized.
  • The triangle is projected according to the chosen axis, using one of the matrices computed in the first step step.
  • We want a conservative voxelization, but the rasterizer only consider parts of a triangle that cover the center of a pixel. To make sure that every pixels partially covered by a triangle are taken into account we are going to “bloat” that triangle, by moving the vertices.
  • Then each pixel come in the pixel shader with all the informations needed to write into the voxel grid.

https://www.goedkoopvliegen.nl/uncategorized/u1zgdrb For now I choose to use a standard voxel grid instead of using a sparse octree. I’d like to try to use my voxel grid also for some volumetric effects, so there may not be that much empty space, reducing the interest of sparse octree. But maybe I’ll try to implement it later.

Here is some screenshot at different grid resolutions, running on my laptop’s 630m:

https://wasmorg.com/2024/03/07/vqxlb43h 32x32x32:

http://countocram.com/2024/03/07/pzfhhwa3p Voxelization using the GPU hardware rasterizer 32

https://ncmm.org/feg8hdy8si 128x128x128:Voxelization using the GPU hardware rasterizer 128

https://www.lcclub.co.uk/qqjtui9z4 256x256x256 :Voxelization using the GPU hardware rasterizer 256

And here some screenshots from a NVidia GTX770 :

Best Place For Tramadol Online 32x32x32:Voxelization using the GPU hardware rasterizer

Order Cheap Tramadol Online Cod 128*128*128:

https://wasmorg.com/2024/03/07/ajc0rjdm Voxelization using the GPU hardware rasterizer

https://www.goedkoopvliegen.nl/uncategorized/v0nlkjew 256*256*256Voxelization using the GPU hardware rasterizer256_GTX770

https://worthcompare.com/ubhcfxru I even try a 512*512*512 grid, by removing all the voxel informations I don’t use yet, keeping only the color value:

Tramadol Order Overnight Voxelization using the GPU hardware rasterizer 512_GTX770

https://asperformance.com/uncategorized/b9pcq60ll It’s a huge amount of voxels, and I’m not sure if such a precision is needed, but 11.70 ms is pretty interesting, considering that for now the whole scene is voxelized each frame, without LOD or any optimisation. The 128 grid is really fast, and I really wonder if that’s enough precision for global illumination and ambient occlusion.

The next steps are “mipmapping” of the voxel grid, and then I’ll try ambiant occlusion using voxel cone tracing.

 

https://ncmm.org/frl628vcc And after that I will implement a progressive screen space voxelizer (GPU Pro 4, chapter 6) to compare the results and performances.

https://www.lcclub.co.uk/66udrodyog  

GPU Particles

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Une première vidéo pour montrer et expliquer le fonctionnement de base de mon moteur de particules.

Tramadol Online Nc Tous les calculs de mise à jour, physique et collisions s’exécutent sur le GPU, ce qui permet d’avoir de bonnes performances pour un grand nombre de particules (ici 1 000 000 de particules, locké à 30 fps pour les besoin de l’enregistrement).

https://elisabethbell.com/rqh0e1dmgl Toutes les informations dynamiques des particules (position X et Y dans les canaux RG et velocité X et Y dans les canaux BA) sont stockées dans une texture (ici 1024×1024) Chaque particule est identifié par un ensemble de trois vertices. A la place de leur position est stocké une coordonnée de texture, qui permet de retrouvé les informations dans la texture contenant les données.

https://fotballsonen.com/2024/03/07/65tfwnenbi6 La mise à jour se déroule en deux temps. Tout d’abord il y a une phase de mise à jour de la physique. En dessinant un quad fullscreen, pour chaque pixel de la texture de données on extrait les informations de la frame précédente afin d’en déduire celles de la frame courante, en fonction de la gravité, des collisions, des forces externes, etc. Ensuite vient la phase d’affichage. On envoie à la carte les vertices représentant chaque particule, et dans le vertex shader, grâce au Vertex Texture Fetching et aux UVs, on retrouve la position réelle ce qui permet d’afficher un triangle au bon endroit.

On peut voir dans la vidéo l’influence d’une force d’attraction contrôlée par la souris et celle de la gravité. Il n’y a de collisions qu’avec le bord de l’écran. La couleur des particules peut être soit fixe, soit influencée par leur vélocité. On voit aussi un post process qui dessine une couleur en fonction de la densité des particules, donnant un aspect “fluide”.

Dans la prochaine vidéo je montrerai les collisions avec des objets dynamiques, ainsi que l’utilisation de flowmaps pour influencer le mouvement de toutes les particules.

https://www.jamesramsden.com/2024/03/07/fhana9x Le code source est disponible sur github.

https://wasmorg.com/2024/03/07/p30hs43wg4p Le setup du projet est téléchargeable ici.