OpenGL Precompute Vertices/Matrices for Particle System / Optimization
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I have a particle system which I want to make as really fast as possible without any effects on the main display function, I basically placed all particles calculations on a separate infinite thread which I keep synchronized with WaitForEvent() (Windows), DataLock flags, etc.
I use glColorPointer, glNormalPointer, glVertexPointer etc to point to the buffered data on the GPU (glGenBuffers, glBufferData) and then glDrawElements to render them.
At the moment I don't have the code so I hope that won't be a problem but I'll try my best to get the infrastructure described:
Main [Init]
- Create a pre-calc queue 30% in size of N particles and do sequential calculations (Thread 1 #2)
Thread 1
- Wait for Calculate Event signal or if pre-calc queue is not full then continue
- Loop through N particles and update position / velocity, storing it in pUpdate
- If pre-calc queue is not full, add pUpdate to it
Main [Render]
- glActiveTexture(TEXTURE0)
- glCol/glNorm/glTex/glVertexPointer
- If pre-calc is empty use the most recent pUpdate
- OR use one of the pre-calc and delete
- Store item in buffer using glBufferSubData()
- DrawElements() to draw them
- SwapBuffers
The problem is that the Render function uses about 50 pre-calc per second (which speeds up rendering while there are enough left) before 1 could even be added. In short order the pre-calc is empty so everything slows down and the program reverts to Main-Render #3
Any ideas?
c++ opengl optimization vbo particle-system
edited Nov 14 at 23:05
genpfault
41.3k95197
asked Nov 14 at 22:56
Takii Marskii
87
|
show 1 more comment
up vote
0
down vote
favorite
I have a particle system which I want to make as really fast as possible without any effects on the main display function, I basically placed all particles calculations on a separate infinite thread which I keep synchronized with WaitForEvent() (Windows), DataLock flags, etc.
I use glColorPointer, glNormalPointer, glVertexPointer etc to point to the buffered data on the GPU (glGenBuffers, glBufferData) and then glDrawElements to render them.
At the moment I don't have the code so I hope that won't be a problem but I'll try my best to get the infrastructure described:
Main [Init]
- Create a pre-calc queue 30% in size of N particles and do sequential calculations (Thread 1 #2)
Thread 1
- Wait for Calculate Event signal or if pre-calc queue is not full then continue
- Loop through N particles and update position / velocity, storing it in pUpdate
- If pre-calc queue is not full, add pUpdate to it
Main [Render]
- glActiveTexture(TEXTURE0)
- glCol/glNorm/glTex/glVertexPointer
- If pre-calc is empty use the most recent pUpdate
- OR use one of the pre-calc and delete
- Store item in buffer using glBufferSubData()
- DrawElements() to draw them
- SwapBuffers
The problem is that the Render function uses about 50 pre-calc per second (which speeds up rendering while there are enough left) before 1 could even be added. In short order the pre-calc is empty so everything slows down and the program reverts to Main-Render #3
Any ideas?
c++ opengl optimization vbo particle-system
edited Nov 14 at 23:05
genpfault
41.3k95197
asked Nov 14 at 22:56
Takii Marskii
87
Why aren't you performing the particle calculations on the GPU?
– 3Dave
Nov 14 at 22:59
Alright thats a start! So how I worked it out is that the shader would basically do the Velocity and Positions calculations per vertex, how would I get the updated position back to the Client side so the next time it can be done again?
– Takii Marskii
Nov 14 at 23:03
There are two ways of doing it on the GPU that I know of. You can either use transform feedback to update the VBO or use a texture to store the positions and render into the texture. Eitehr way you want to avoid copying the position back to the client (cpu) as that is an expensive operation.
– Luple
Nov 15 at 0:34
I don't know which OpenGL version you're using, but if it's supported your best option is a compute shader with ssbo. You first update the particles in the ssbo with the compute shader, place a barrier and then draw using the same buffer as input for vertex shader.
– Rhu Mage
Nov 15 at 7:28
@Luple Thanks so much I'll go and try both methods but honestly transform feedback seems to be my favourite
– Takii Marskii
Nov 15 at 20:59
|
show 1 more comment
up vote
0
down vote
favorite
up vote
0
down vote
favorite
I have a particle system which I want to make as really fast as possible without any effects on the main display function, I basically placed all particles calculations on a separate infinite thread which I keep synchronized with WaitForEvent() (Windows), DataLock flags, etc.
I use glColorPointer, glNormalPointer, glVertexPointer etc to point to the buffered data on the GPU (glGenBuffers, glBufferData) and then glDrawElements to render them.
At the moment I don't have the code so I hope that won't be a problem but I'll try my best to get the infrastructure described:
Main [Init]
- Create a pre-calc queue 30% in size of N particles and do sequential calculations (Thread 1 #2)
Thread 1
- Wait for Calculate Event signal or if pre-calc queue is not full then continue
- Loop through N particles and update position / velocity, storing it in pUpdate
- If pre-calc queue is not full, add pUpdate to it
Main [Render]
- glActiveTexture(TEXTURE0)
- glCol/glNorm/glTex/glVertexPointer
- If pre-calc is empty use the most recent pUpdate
- OR use one of the pre-calc and delete
- Store item in buffer using glBufferSubData()
- DrawElements() to draw them
- SwapBuffers
The problem is that the Render function uses about 50 pre-calc per second (which speeds up rendering while there are enough left) before 1 could even be added. In short order the pre-calc is empty so everything slows down and the program reverts to Main-Render #3
Any ideas?
c++ opengl optimization vbo particle-system
edited Nov 14 at 23:05
genpfault
41.3k95197
asked Nov 14 at 22:56
Takii Marskii
87
I have a particle system which I want to make as really fast as possible without any effects on the main display function, I basically placed all particles calculations on a separate infinite thread which I keep synchronized with WaitForEvent() (Windows), DataLock flags, etc.
I use glColorPointer, glNormalPointer, glVertexPointer etc to point to the buffered data on the GPU (glGenBuffers, glBufferData) and then glDrawElements to render them.
At the moment I don't have the code so I hope that won't be a problem but I'll try my best to get the infrastructure described:
Main [Init]
- Create a pre-calc queue 30% in size of N particles and do sequential calculations (Thread 1 #2)
Thread 1
- Wait for Calculate Event signal or if pre-calc queue is not full then continue
- Loop through N particles and update position / velocity, storing it in pUpdate
- If pre-calc queue is not full, add pUpdate to it
Main [Render]
- glActiveTexture(TEXTURE0)
- glCol/glNorm/glTex/glVertexPointer
- If pre-calc is empty use the most recent pUpdate
- OR use one of the pre-calc and delete
- Store item in buffer using glBufferSubData()
- DrawElements() to draw them
- SwapBuffers
The problem is that the Render function uses about 50 pre-calc per second (which speeds up rendering while there are enough left) before 1 could even be added. In short order the pre-calc is empty so everything slows down and the program reverts to Main-Render #3
Any ideas?
c++ opengl optimization vbo particle-system
c++ opengl optimization vbo particle-system
edited Nov 14 at 23:05
genpfault
41.3k95197
asked Nov 14 at 22:56
Takii Marskii
87
edited Nov 14 at 23:05
genpfault
41.3k95197
asked Nov 14 at 22:56
Takii Marskii
87
edited Nov 14 at 23:05
genpfault
41.3k95197
edited Nov 14 at 23:05
genpfault
41.3k95197
edited Nov 14 at 23:05
genpfault
41.3k95197
41.3k95197
asked Nov 14 at 22:56
Takii Marskii
87
asked Nov 14 at 22:56
Takii Marskii
87
asked Nov 14 at 22:56
Takii Marskii
87
87
Why aren't you performing the particle calculations on the GPU?
– 3Dave
Nov 14 at 22:59
Alright thats a start! So how I worked it out is that the shader would basically do the Velocity and Positions calculations per vertex, how would I get the updated position back to the Client side so the next time it can be done again?
– Takii Marskii
Nov 14 at 23:03
There are two ways of doing it on the GPU that I know of. You can either use transform feedback to update the VBO or use a texture to store the positions and render into the texture. Eitehr way you want to avoid copying the position back to the client (cpu) as that is an expensive operation.
– Luple
Nov 15 at 0:34
I don't know which OpenGL version you're using, but if it's supported your best option is a compute shader with ssbo. You first update the particles in the ssbo with the compute shader, place a barrier and then draw using the same buffer as input for vertex shader.
– Rhu Mage
Nov 15 at 7:28
@Luple Thanks so much I'll go and try both methods but honestly transform feedback seems to be my favourite
– Takii Marskii
Nov 15 at 20:59
|
show 1 more comment
Why aren't you performing the particle calculations on the GPU?
– 3Dave
Nov 14 at 22:59
Alright thats a start! So how I worked it out is that the shader would basically do the Velocity and Positions calculations per vertex, how would I get the updated position back to the Client side so the next time it can be done again?
– Takii Marskii
Nov 14 at 23:03
There are two ways of doing it on the GPU that I know of. You can either use transform feedback to update the VBO or use a texture to store the positions and render into the texture. Eitehr way you want to avoid copying the position back to the client (cpu) as that is an expensive operation.
– Luple
Nov 15 at 0:34
I don't know which OpenGL version you're using, but if it's supported your best option is a compute shader with ssbo. You first update the particles in the ssbo with the compute shader, place a barrier and then draw using the same buffer as input for vertex shader.
– Rhu Mage
Nov 15 at 7:28
@Luple Thanks so much I'll go and try both methods but honestly transform feedback seems to be my favourite
– Takii Marskii
Nov 15 at 20:59
Why aren't you performing the particle calculations on the GPU?
– 3Dave
Nov 14 at 22:59
Why aren't you performing the particle calculations on the GPU?
– 3Dave
Nov 14 at 22:59
Alright thats a start! So how I worked it out is that the shader would basically do the Velocity and Positions calculations per vertex, how would I get the updated position back to the Client side so the next time it can be done again?
– Takii Marskii
Nov 14 at 23:03
Alright thats a start! So how I worked it out is that the shader would basically do the Velocity and Positions calculations per vertex, how would I get the updated position back to the Client side so the next time it can be done again?
– Takii Marskii
Nov 14 at 23:03
There are two ways of doing it on the GPU that I know of. You can either use transform feedback to update the VBO or use a texture to store the positions and render into the texture. Eitehr way you want to avoid copying the position back to the client (cpu) as that is an expensive operation.
– Luple
Nov 15 at 0:34
There are two ways of doing it on the GPU that I know of. You can either use transform feedback to update the VBO or use a texture to store the positions and render into the texture. Eitehr way you want to avoid copying the position back to the client (cpu) as that is an expensive operation.
– Luple
Nov 15 at 0:34
I don't know which OpenGL version you're using, but if it's supported your best option is a compute shader with ssbo. You first update the particles in the ssbo with the compute shader, place a barrier and then draw using the same buffer as input for vertex shader.
– Rhu Mage
Nov 15 at 7:28
I don't know which OpenGL version you're using, but if it's supported your best option is a compute shader with ssbo. You first update the particles in the ssbo with the compute shader, place a barrier and then draw using the same buffer as input for vertex shader.
– Rhu Mage
Nov 15 at 7:28
@Luple Thanks so much I'll go and try both methods but honestly transform feedback seems to be my favourite
– Takii Marskii
Nov 15 at 20:59
@Luple Thanks so much I'll go and try both methods but honestly transform feedback seems to be my favourite
– Takii Marskii
Nov 15 at 20:59
|
show 1 more comment
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Why aren't you performing the particle calculations on the GPU?
– 3Dave
Nov 14 at 22:59
Alright thats a start! So how I worked it out is that the shader would basically do the Velocity and Positions calculations per vertex, how would I get the updated position back to the Client side so the next time it can be done again?
– Takii Marskii
Nov 14 at 23:03
There are two ways of doing it on the GPU that I know of. You can either use transform feedback to update the VBO or use a texture to store the positions and render into the texture. Eitehr way you want to avoid copying the position back to the client (cpu) as that is an expensive operation.
– Luple
Nov 15 at 0:34
I don't know which OpenGL version you're using, but if it's supported your best option is a compute shader with ssbo. You first update the particles in the ssbo with the compute shader, place a barrier and then draw using the same buffer as input for vertex shader.
– Rhu Mage
Nov 15 at 7:28
@Luple Thanks so much I'll go and try both methods but honestly transform feedback seems to be my favourite
– Takii Marskii
Nov 15 at 20:59