-- One image used by several maps of a glTF is uploaded once for each way the maps read it, not once
-- a map:  Models/OneImage.gltf uses its 256x256 picture once, as a base colour, which sets the size
-- of an upload;  Models/SharedImage.gltf has two materials that each use the same picture for all
-- five maps, which is two uploads (the base and emissive maps read it as sRGB, the other three as
-- data), not ten.  Deleting each model has to give every byte back, which proves the shared texture
-- outlives the first material to let go of it and goes with the last.  Each check prints
-- "SHARED ok" or "SHARED FAIL".  No disc:  run with -C 720x480.
dofile("Singe/Framework.singe")

local font     = fontLoad("Singe/FreeSansBold.ttf", 14)
local camera   = nodeNew()
local sun      = lightNew(LIGHT_DIRECTIONAL)
local frames   = 0
local failures = 0
local before   = 0
local single   = 0
local model    = nil
local LAST     = 12


local function check(name, ok, detail)
	if ok then
		debugPrint("SHARED ok " .. name)
	else
		failures = failures + 1
		debugPrint("SHARED FAIL " .. name .. (detail and ("  (" .. detail .. ")") or ""))
	end
end


-- Kilobytes of texture the scene holds now.
local function textureKb()
	local _, _, _, kb = sceneGetStats()

	return kb
end


fontSelect(font)
overlaySetResolution(720, 480)
sceneEnable(true)
cameraSet(camera)
nodeSetPosition(camera, 0.5, 0.5, 2)
nodeLookAt(camera, 0.5, 0.5, 0)
nodeLookAt(sun, -1, -2, -1)


function onOverlayUpdate()
	frames = frames + 1
	overlayClear()
	fontPrint(8, 6, string.format("frame %d  textures %d KB  failures %d", frames, textureKb(), failures))
	if frames == 2 then
		before = textureKb()
		model  = modelLoad("testScripts/Models/OneImage.gltf")
		modelInstance(model)
	elseif frames == 4 then
		single = textureKb() - before
		check("one upload costs something", single > 0, single .. " KB")
		modelDelete(model)
	elseif frames == 6 then
		check("modelDelete gives the one upload back", textureKb() == before, textureKb() .. " KB against " .. before)
		model = modelLoad("testScripts/Models/SharedImage.gltf")
		modelInstance(model)
	elseif frames == 8 then
		local shared = textureKb() - before

		check("ten maps of one image are two uploads", shared == 2 * single, shared .. " KB against " .. (2 * single))
		singeScreenshot("shared")
		modelDelete(model)
	elseif frames == 10 then
		check("modelDelete gives the shared uploads back", textureKb() == before, textureKb() .. " KB against " .. before)
	elseif frames == LAST then
		debugPrint(string.format("SHARED RESULT failures=%d", failures))
		singeQuit()
	end
	return OVERLAY_UPDATED
end