Camera::SetRealtime(false) performance issue

[Vladimir Sabantsev]

Hello,

I'm trying to distribute my additional cameras rendering across different frames to boost performance. Unfortunately, setting Camera::SetRealtime(false) doesn't have any positive effect on the frame count.

In case of the following example I get FPS drop from 600 to 480 when I add 12 inactive cameras for depth cubemap capture:

#include "Leadwerks.h"
namespace lwe = Leadwerks;

int main(int argc, const char* argv[])
{
  auto displays    = lwe::GetDisplays();
  auto window      = lwe::CreateWindow("Leadwerks", 0, 0, displays[0]->size.x, displays[0]->size.y, displays[0], lwe::WINDOW_FULLSCREEN);
  auto framebuffer = lwe::CreateFramebuffer(window);
  auto world       = lwe::CreateWorld();

  auto light  = lwe::CreateDirectionalLight(world);
  auto sphr_c = lwe::CreateSphere(world);
  auto cone_0 = lwe::CreateCone(world, 0.5f, 1.f, 64);
  auto sphr_0 = lwe::CreateSphere(world);
  auto cube_0 = lwe::CreateBox(world);
  auto cone_1 = lwe::CreateCone(world, 0.5f, 1.f, 64);
  auto sphr_1 = lwe::CreateSphere(world);
  auto cube_1 = lwe::CreateBox(world);
  auto cube_f = lwe::CreateBox(world);
  auto clnd_0 = lwe::CreateCylinder(world, 0.5f, 1.f, 64);

  cube_f->SetScale(100.f, 1.f, 100.f);
  cube_f->SetPosition(0.f, -3.001f, 0.f);

  light->SetRotation(60, 0, 0);
  light->SetColor(0.5f);
  world->SetAmbientLight(0.05f, 0.1f, 0.1f);

  sphr_c->SetScale(0.3f);
  cone_1->SetScale(1.5f);

  cone_0->SetPosition( 0.f, +1.f, +2.f);
  sphr_0->SetPosition(+2.f, +1.f,  0.f);
  cube_0->SetPosition(+1.f, +2.f, +1.f);
  cone_1->SetPosition( 0.f, -1.f, -2.f);
  sphr_1->SetPosition(-2.f, -1.f,  0.f);
  cube_1->SetPosition(-1.f, -2.f, -1.f);
  clnd_0->SetPosition(-2.1f, -2.f, -1.f);

#if 1
  std::vector<std::shared_ptr<lwe::Camera>> extra_camera_vec;
  auto texture_1 = lwe::CreateTexture(lwe::TEXTURE_CUBE, 1024, 1024, lwe::TEXTURE_DEPTH, {}, 6);
  auto texture_2 = lwe::CreateTexture(lwe::TEXTURE_CUBE, 1024, 1024, lwe::TEXTURE_DEPTH, {}, 6);

  for (uint32_t i = 0; i < 6; ++i)
  {
    auto texbuff = lwe::CreateTextureBuffer(1024, 1024, 0, true);
    texbuff->SetDepthAttachment(texture_1, i);

    auto camera = lwe::CreateCamera(world);
    camera->SetRenderTarget(texbuff);
    camera->SetRealtime(false);

    extra_camera_vec.push_back(camera);
  }

  for (uint32_t i = 0; i < 6; ++i)
  {
    auto texbuff = lwe::CreateTextureBuffer(1024, 1024, 0, true);
    texbuff->SetDepthAttachment(texture_2, i);

    auto camera = lwe::CreateCamera(world);
    camera->SetRenderTarget(texbuff);
    camera->SetRealtime(false);

    extra_camera_vec.push_back(camera);
  }
#endif

  auto main_camera = CreateCamera(world);
  while (!window->Closed() && !window->KeyDown(lwe::KEY_ESCAPE))
  {
    world->Update();
    world->Render(framebuffer, false, 9999);
  }

  return 0;
}

In my project this performance drop is much more noticeable - from ~600 to ~120 no matter if SetRealtime is true or false on pretty much the same scene, but I'm not sure what else contributes to it. I would expect inactive cameras to have virtually no effect on performance.