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Forums - Gaming Discussion - Need an Answer to a slightly technical question

Intrinsic on 13 February 2019

Alright, lets take the PS4 GPU as a base. So we have 1.8TF.

How exactly does a games render engine utilize this? Does it all boil down to some sort of render time allotment??

To elaborate.

A dev wants to run their game at 30fps. That translates to generating a complete image every 33ms. So is it something like this?

 

  • 1ms-8ms = Geometry
  • 9ms-18ms = rasterization (this is when they have pixels)
  • 19ms-25ms = shading
  • 26ms-30m = color
  • 31ms-33ms = post processing
The above will mean that only a specific amount of time can be spent on any one area and some of those areas are dependent on other aspects of the hardware (cpu, bandwidth..etc). Which would mean that at some point the PS4 uses all f its GPU to handle just resolution (rasterization) and then the next all of its GPU to handle the shading...etc
Can someone correct, confirm or shed more light on what I a asking here if any f this makes sense? Not sure I am saying it right.

 



Yerm on 13 February 2019

gonna need to deconstruct that a bit. so you want a game to run at 30fps - for specifically talking about the GPU, it first has to render the environment. first the geometry is loaded, then the textures, then the shadows, and finally post-processing and anti-aliasing are added on top of the final image. but from then on, its done. when your character moves through a 3D environment, the only things that need to be updated are the Player Character and the camera, which is usually derivative of the player. the post-processing and anti-aliasing are the only things that need to be updated every frame, because they act as a filtering layer on top of the graphics



Intrinsic on 13 February 2019
Yerm said:
gonna need to deconstruct that a bit. so you want a game to run at 30fps - for specifically talking about the GPU, it first has to render the environment. first the geometry is loaded, then the textures, then the shadows, and finally post-processing and anti-aliasing are added on top of the final image. but from then on, its done. when your character moves through a 3D environment, the only things that need to be updated are the Player Character and the camera, which is usually derivative of the player. the post-processing and anti-aliasing are the only things that need to be updated every frame, because they act as a filtering layer on top of the graphics

That doesn't sound right.... or am I missing something?

This makes it sound like after the first frame is created the GPU doesn't have much else to do for all subsequent frames. So what so what happens when there is an expolsion? a building collapses? some NPCs r even the player (if third person) appears on screen.... with every new frame not only are all of these things in a new position, but animation means that they may also look different. 

Doesnt that mean that the entire scene is redrawn with every frame? 

I know there are things that deosnt have t be drawn from scratch every frame but.......



Yerm on 14 February 2019
Intrinsic said:
Yerm said:
gonna need to deconstruct that a bit. so you want a game to run at 30fps - for specifically talking about the GPU, it first has to render the environment. first the geometry is loaded, then the textures, then the shadows, and finally post-processing and anti-aliasing are added on top of the final image. but from then on, its done. when your character moves through a 3D environment, the only things that need to be updated are the Player Character and the camera, which is usually derivative of the player. the post-processing and anti-aliasing are the only things that need to be updated every frame, because they act as a filtering layer on top of the graphics

That doesn't sound right.... or am I missing something?

This makes it sound like after the first frame is created the GPU doesn't have much else to do for all subsequent frames. So what so what happens when there is an expolsion? a building collapses? some NPCs r even the player (if third person) appears on screen.... with every new frame not only are all of these things in a new position, but animation means that they may also look different. 

Doesnt that mean that the entire scene is redrawn with every frame? 

I know there are things that deosnt have t be drawn from scratch every frame but.......

during an animation, the models and textures dont have to be redrawn, they just have to be moved. in the case of an explosion, the whole explosion has to be rendered and animated