[rlgl] Add rlCullDistance variables/getters and rlSetClipPlanes function

[KotzaBoss]

NOTE: The PR at the moment is just a proof-of-concept to show the scale of modifications necessary to make this happen. Should it be reviewed well i will add the utils for rlClipDistanceNear and fix any use of RL_CULL_DISTANCE*, for example in the camera. Also i am not too sure about the name, when "cull" when "clip"

Reasoning

As discussed on discord here and then mentioned here the current CULL_DISTANCEs are hardcoded and require a full recompile to change.

By adding static rlCullDistance globals and accessor function we can make this a runtime configurable value.

Overview:

The current RL_CULL_DISTANCE_ remain as configuration of the initial cull distances. New code may include:

• Static variables:
  • rlCullDistanceFar
  • rlCullDistanceNear
• Accessors:
  • rlGetClipPlaneNear()
  • rlGetClipPlaneFar()
  • rlGetDefaultClipPlaneNear()
  • rlGetDefaultClipPlaneFar()
• Setters:
  • rlSetClipPlanes(double near, double far)
  • rlSetClipPlaneNear(double value)
  • rlSetClipPlaneFar(double value)
  • rlResetClipPlanes()

Example

Screencast.from.2024-04-11.11-11-42.webm

[raysan5]

@KotzaBoss Thanks for draft. Please, could you share some use case where clip planes need to be dynamically changed? I feel this functionality is very limited in scope, only useful for very specific circunstances.

Still, I can consider adding a rlSetClipPlanes(), in raylib I priorityze minimalism, I can't see the need for more than one function.

[KotzaBoss]

Even the rlSetClipPlanes is enough imo, i wrote the extended functions for completeness. Essentially all i proposed can be reduced to:

#include <raylib.h>
#include <rlgl.h>

#define MY_CULL_DISTANCE_FAR 5000.0

rlSetClipPlanes(RL_CULL_DISTANCE_NEAR, MY_CULL_DISTANCE_FAR);

if (i_must_reset_cull_distance)
    rlSetClipPlanes(RL_CULL_DISTANCE_NEAR, RL_CULL_DISTANCE_FAR);

Though internaly there may need to be some change from using the RL_CULL_DISTANCE_ to using some Get functions or accessing the static variables directly. I am not sure about thread safety in raylib so i suppose getters would be safer.

Is this acceptable?

[raysan5]

Is this acceptable?

Yes, that would be perfect

[KotzaBoss]

As of now the camera is just defining its own CAMERA_CULL_DISTANCE to be the config's RL_CULL_DISTANCE. For the test i present i did not change anything in the camera and it works.

Are my changes therefore enough?

[electrolys]

@KotzaBoss Thanks for draft. Please, could you share some use case where clip planes need to be dynamically changed? I feel this functionality is very limited in scope, only useful for very specific circunstances.

Still, I can consider adding a rlSetClipPlanes(), in raylib I priorityze minimalism, I can't see the need for more than one function.

i would have to change the far plane in my voxel game all the time for different render distances if i didn't just switch to a infinite projection matrix

[raysan5]

@KotzaBoss Thanks for the improvement, merging!

[paulmelis]

@KotzaBoss Thanks for draft. Please, could you share some use case where clip planes need to be dynamically changed? I feel this functionality is very limited in scope, only useful for very specific circunstances.

Thanks for merging rlSetClipPlanes(). Another case where you want control over near/far ranges is when rendering shadow maps. There you want control over the depth range to maximize use of depth precision.