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Re: GL4ES: another OpenGL over OpenGLES2 emulation - some tech. info and porting progress

Subject: Re: GL4ES: another OpenGL over OpenGLES2 emulation - some tech. info and porting progress
by thellier on 2019/9/17 14:15:15

> the same data ? I mean , if there is DMA to transfer bitmap to VRAM

Yes,For Wazp3D57 I have made some code that hack a bitmap transfer to be used to copy vertices to VBO.
(ouuh what a hack but it works )

It changed almost nothing to speed on Sam460 & X5000 but dont know if those machines use dma for that

>about BufferUnlock of warp3dnova, there is no mention about any big->little endian conversion

IMHO what I understood:
There are differents method for updating the VBO
but in fact Nova just read and/or write the data
When you lock it (can) read/reorder the VBO data to a buffer that you will access.
When you unlock it (can) write/reorder the buffer to the VBO data.
As reordering is done Nova side you never accesss to real data that are on the GPU VRAM but on a reordered buffer

You can also do write only (ie write all new vertices values from your buffer)
or read only (ie read some GPU datas)
or read/write (ie change some vertices)

Certainly let Nova do the reordering was not a good idea as datas are then acessed several times (vs a cpu that will write to real GPU vram directly the reordered datas)

See below Nova doc
// W3DN_STATIC_DRAW: Written:(CPU) once Read: rendered many times
// W3DN_STATIC_READ: Written:(GPU) once Read: CPU many times
// W3DN_STATIC_COPY: Written:(GPU) once Read: rendered many times
// W3DN_DYNAMIC_DRAW: Written:(CPU) occasionally Read: rendered many times
// W3DN_DYNAMIC_READ: Written:(GPU) occasionally Read: CPU many times
// W3DN_DYNAMIC_COPY: Written:(GPU) occasionally Read: rendered many times
// W3DN_STREAM_DRAW: Written:(CPU) frequently Read: rendered a few times
// W3DN_STREAM_READ: Written:(GPU) frequently Read: CPU a few times
// W3DN_STREAM_COPY: Written:(GPU) very often Read: rendered a few times



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