Starfall screen will render twice per frame if map has water

[thegrb93]

Yes, I know it's for the water effect, but this is problematic for user code that relies on timing or performance.

[Advers]

A preferred solution would allow users to exit any render hook early, and not just screens. Also, it would be great if it was optional, in the case where we do want to allow rendering in reflections, or maybe even only in reflections for some interesting possibilities.

[thegrb93]

was thinking maybe moving the screen rendering into postdrawopaquerenderables hook or something. this would also allow the screen to draw despite the model being invisible

[thegrb93]

It wouldn't have correct draw ordering with respect to other translucent things though

[Advers]

was thinking maybe moving the screen rendering into postdrawopaquerenderables hook or something. this would also allow the screen to draw despite the model being invisible

That on its own shouldn't work, because DrawOpaqueRenderables also gets called for water reflections

[Advers]

Suggestion: If it's possible to find out "where" in the render hook order a given hook is when it's called, there could be a function that returns a boolean for if a hook is being called for DrawWaterReflections or not. If there isn't a way to do this directly, maybe it can be done by observing the order render hooks are called in when near water vs when not.

[thegrb93]

Marking this as a gmod bug since there doesn't seem to be any way to differentiate water drawing. Might need to resort to CurTime or something.

[Cheatoid]

I believe there is a way to detect a "water pass", but it would involve a couple of hooks.
Meanwhile, can you check whether SF screen is rendered twice when using those console variables - before loading into the map:

mat_specular 0;r_WaterDrawReflection 0;r_WaterDrawRefraction 0;r_waterforceexpensive 0;r_waterforcereflectentities 0;

---

after some digging into mat_showwatertextures 1...

local ITexture_GetName = FindMetaTable("ITexture").GetName
local string_find, string_lower = string.find, string.lower
-- https://github.com/ValveSoftware/source-sdk-2013/blob/7191ecc418e28974de8be3a863eebb16b974a7ef/src/game/client/rendertexture.cpp#L133
local WaterPassLookup = {
  -- NOTE: these are lower-case names of the render targets used by the engine for water effects
  _rt_waterreflection = true,
  _rt_waterrefraction = true,
}
-- https://wiki.facepunch.com/gmod/Render_Order#drawwaterreflections
local isInWaterPass = false
-- setting up world fog (also called during water reflection, i guess)
hook.Add("SetupWorldFog", "DetectWaterPass", function()
  -- check if this is likely a water reflection/refraction pass
  local currentRT = render.GetRenderTarget()
  if currentRT then
    local rtName = string_lower(ITexture_GetName(currentRT))
    if WaterPassLookup[rtName] or string_find(rtName, "waterreflection", 1, true) or string_find(rtName, "waterrefraction", 1, true) then
      isInWaterPass = true
      print("[SetupWorldFog] pre-water rendering")
    else
      isInWaterPass = false
    end
  else
    isInWaterPass = false
  end
end)
hook.Add("PostDrawOpaqueRenderables", "DetectWaterPassOpaque", function(bDrawingDepth, bDrawingSkybox)
  if not bDrawingDepth and not bDrawingSkybox then
    -- this is called *during* world rendering and water reflection/refraction
    print("[PostDrawOpaqueRenderables] isInWaterPass:", isInWaterPass)
  end
end)
-- detect when water rendering is done
hook.Add("PostRender", "WaterPassEnd", function()
  if isInWaterPass then
    isInWaterPass = false
    print("[PostRender] post-water rendering")
  end
end)

---

Actually it may not even require using hooks... Potential fix:

local ITexture_GetName = FindMetaTable("ITexture").GetName
local string_find, string_lower = string.find, string.lower
-- https://github.com/ValveSoftware/source-sdk-2013/blob/7191ecc418e28974de8be3a863eebb16b974a7ef/src/game/client/rendertexture.cpp#L133
local WaterPassLookup = {
  -- NOTE: These are lower-case names of the render targets used by the engine for water reflections and refractions
  _rt_waterreflection = true,
  _rt_waterrefraction = true,
}
-- https://wiki.facepunch.com/gmod/Render_Order#drawwaterreflections
-- This is the main rendering hook, RenderOverride gives more control
function ENT:RenderOverride(studioFlags)
  -- TODO: Perhaps check studioFlags too:
  --print("[studioFlags]", self, studioFlags)
  --if studioFlags ~= STUDIO_RENDER then return end -- https://wiki.facepunch.com/gmod/Enums/STUDIO
  -- Detect and skip water-pass, I guess...
  -- Get the current render target that the engine is drawing to
  local currentRT = render.GetRenderTarget()
  -- Make sure we have a render target
  if currentRT then
    -- Check if the render target's name indicates a water-pass
    local rtName = string_lower(ITexture_GetName(currentRT))
    -- Source engine uses specific named render targets for water effects
    --print("[rtName]", self, rtName)
    -- TODO: Perhaps use a lookup table once we capture their actual names
    if WaterPassLookup[rtName] or string_find(rtName, "waterreflection", 1, true) or string_find(rtName, "waterrefraction", 1, true) then
      -- We are in a water reflection or refraction pass
      -- By returning here, we prevent the SF screen from being drawn this time
      return
    end
  end
  -- Now we are in the main world render, we can safely draw SF screen...
  self:DrawModel()
end