GLSL Error Handling

[Argh]

gl.CreateShader is causing Spring to crash, if the hardware cannot run shaders.

Why is it doing that? I can understand that callout not working, and returning a false result when it tries to compile, but it should attempt to run... and it's causing a crash, instead. Anybody know why?

[Kloot]

You need to read error messages a little better:

attempt to call field 'CreateShader' (a nil value)

Code: Select all

if (gl.CreateShader == nil) then
    Spring.Echo("oh snap")
    gadgetHandler:RemoveGadget()
end

[Argh]

But why is that field missing?

[Kloot]

Because the Lua OGL environment only makes the callout available (== non-nil) when

Code: Select all

haveGL20 && !!configHandler.Get("LuaShaders", 1)

since otherwise

glCreateShader is causing Spring to crash

would actually be true.

[Argh]

Okie doke. Seems like it would be better to have it run a function that does nothing, imo, instead of causing a crash. At least now I know what's going on.

[lurker]

Silently failing is pretty bad; then you'd be wondering why your shader is empty.

[Argh]

Well, since the crash doesn't happen on any of the hardware we're testing on... not knowing that this was occurring was a major problem.

You guys realize that this has ruined three releases now, for people with hardware that can't do GLSL?

[jK]

You guys realize that this has ruined three releases now, for people with hardware that can't do GLSL?

Ohh, so it is our fault that you didn't read the wiki?

[lurker]

1. Now you have something you need to add to your testing regimen. Run a game without modui or lua shaders. Those are rather obscure settings that can break many assumptions.
2. IIRC you can't make shaders during loading or init on GML spring, so if you make your code compatible there, loading this in a Draw* call the way you're supposed to, the error will simply output and stop that single gadget.

[Argh]

Now you have something you need to add to your testing regimen. Run a game without modui or lua shaders. Those are rather obscure settings that can break many assumptions.

Running the game without modui makes the game unplayable, at a practical level. I have to assume that if people can't run modui, they're below the hardware requirements.

I'll see if running without Lua shaders causes the same crash behavior over here. It'd be good to have some way to test for that particular trap.

[lurker]

Where in the gadget is this code? Inside a function?

[Argh]

It's in Initialize().

I'll move it, if I know where it should go. In a function called from Draw*, you said?

Meh. I really, really gtg now. I'll read this when I get back.

The lua's here:

Code: Select all

function gadget:GetInfo()
  return {
	 name = "GLSL Lighting",
	 desc = "The P.U.R.E. GLSL Realtime lighting implementation.",
	 author = "Argh",
	 date = "November 7, 2008",
	 license = "Public Domain, or the least-restrictive rights in your country of residence",
	 layer = 0,
	 enabled  = true -- loaded by default?
  }
end

if (gadgetHandler:IsSyncedCode()) then
----------------------------------------------------------------------------------------------------------SYNCED
local function CreateLightMe(u, ud, team, p, r, g, b, a)
	p = Spring.GetUnitScriptPiece(u,p)
	r = r / 255
	g = g / 255
	b = b / 255
	a = a / 255
	SendToUnsynced("CreateLight",u, ud, team, p, r, g, b, a)
end

local function DestroyLightMe(u, ud, team)
	SendToUnsynced("DestroyLight",u, ud, team)
end

function gadget:Initialize()
	gadgetHandler:RegisterGlobal("CreateLightMe", CreateLightMe)
	gadgetHandler:RegisterGlobal("DestroyLightMe", DestroyLightMe)
end

function gadget:UnitDestroyed(u,ud,team)
	SendToUnsynced("DestroyLight",u, ud, team)
end

----------------------------------------------------------------------------------------------------------END SYNCED
else
----------------------------------------------------------------------------------------------------------UNSYNCED

----------------------------------------------------------------------------------------------------------INITIALIZE SHADER
function gadget:Initialize()
   if(gl.CreateShader == nil) then
      Spring.Echo("GLSL Light Shader Failed")
      gadgetHandler:RemoveGadget()
      return false
   end

GLSL_LIGHT_Shader = gl.CreateShader({
    vertex = [[
varying vec4 diffuse;
void main()
{
   gl_Position = ftransform();
   vec3 normal = gl_NormalMatrix * gl_Normal;
   vec3 lightVector = gl_LightSource[1].position.xyz - (gl_ModelViewMatrix * gl_Vertex);
   float dist = length(lightVector);
   float attenuation = 1.0 / (gl_LightSource[1].constantAttenuation +
      gl_LightSource[1].linearAttenuation * dist +
      gl_LightSource[1].quadraticAttenuation * dist * dist);
   lightVector = normalize(lightVector);
   float nxDir = max(0.0, dot(normal, lightVector));
   diffuse = gl_FrontMaterial.diffuse * nxDir * attenuation;
}

]],
   fragment = [[
   varying vec4 diffuse;
   void main()
   {
      gl_FragColor = (gl_LightSource[1].ambient + diffuse);
   }
    ]],
})

   if (GLSL_LIGHT_Shader == nil) then
      Spring.Echo("GLSL Light Shader Failed"..gl.GetShaderLog())
	gadgetHandler:RemoveGadget()
      return false
   else
      Spring.Echo("GLSL Light Shader Succeeded")

      UseShader = 1;
   end
end
----------------------------------------------------------------------------------------------------------END INITIALIZE

----------------------------------------------------------------------------------------------------------LIGHT LIST HANDLER
local tinsert = table.insert
local tremove = table.remove
local LightList = {piece, red, green, blue, alpha}
local GetUnitPiecePosDir = Spring.GetUnitPiecePosDir

function gadget:RecvFromSynced(name, u, ud, team, p, r, g, b, a)
	if name == "CreateLight" then
		if LightList[u] ~= nil then
			LightList[u] = nil
			--Spring.Echo("table removed")
		end
		tinsert(LightList,u,{piece = p, red = r, green = g, blue = b, alpha = a})
	end
	if name == "DestroyLight" then
		if LightList[u] ~= nil then
			LightList[u] = nil
			--Spring.Echo("table removed by Destroy")
		end
	end
end
----------------------------------------------------------------------------------------------------------END LIGHT LIST HANDLER

----------------------------------------------------------------------------------------------------------RENDERING	
local x,y,z = 0,0,0
local glDepthTest = gl.DepthTest
local GL_LEQUAL = GL.LEQUAL
local  glCulling =  gl.Culling
local GL_BACK = GL.BACK
local glBlending = gl.Blending
local glLighting = gl.Lighting
local GetUnitPiecePosDir = Spring.GetUnitPiecePosDir
local glLight = gl.Light
local GL_POSITION = GL.POSITION
local glMaterial = gl.Material
local glUseShader = gl.UseShader
local glPolygonOffset = gl.PolygonOffset
local glUnit = gl.Unit
local glResetState = gl.ResetState
local GetVisibleUnits = Spring.GetVisibleUnits
local GetUnitLosState = Spring.GetUnitLosState
local myTeam = Spring.GetLocalAllyTeamID()
local myState

function gadget:DrawWorld()
	if UseShader == 1 then
	local myIDList = GetVisibleUnits(-1,3000,false)
		if myIDList[1] ~= nil then
			for _,myID in ipairs(myIDList) do
				myState = GetUnitLosState(myID,myTeam)
				if  myState["los"] == true then
					if LightList[myID] ~= nil then
						glDepthTest(GL_LEQUAL)
						glCulling(GL_BACK)
						glBlending(true)
						glLighting(true)
						
						x,y,z = GetUnitPiecePosDir(myID,LightList[myID].piece)

						glLight(1,GL_POSITION,x,y,z,1)
						glMaterial ({
						ambient	= {0, 0, 0, 0},
						diffuse	= {LightList[myID].red,LightList[myID].green,LightList[myID].blue,LightList[myID].alpha},
						ambidiff  = {0, 0, 0, 0},
						emission  = {0, 0, 0, 0},
						specular  = {0, 0, 0, 0},
						shininess = 10
						})
						glUseShader(GLSL_LIGHT_Shader)
						glPolygonOffset(-3,-3)
						glUnit(myID,true)
						
						glLight(0,false)
						glPolygonOffset(0,0)
						glResetState()
						glLighting(false)
					end
				end
			end
		end
	end	
end
----------------------------------------------------------------------------------------------------------END
end

[SpliFF]

i suggest:

Code: Select all

local GLSL_LIGHTING_VP = [[
...glsl code...
]]

Or better yet:

Code: Select all

local GLSL_LIGHTING_VP = VFS.Include('../shaders/lighting.vp')

[Otherside]

referring to argh's point about how this has ruined 3 of his releases

if he properly tested on different machines (OS's and hardware)

and had a proper updating method most of these "problems" could be avoided

[rattle]

You don't need different machines, you can disable the shaders, which has the same effect as if it was running on an incapbable GPU.

[clericvash]

You don't need different machines, you can disable the shaders, which has the same effect as if it was running on an incapbable GPU.

+1, it would help to test things through and through before you release, i made many mistakes with my forum software.

[Argh]

Well, now that I know that, I can do that. Didn't know I could. Ah well.