Multisampled buffer produces “GL_INVALID_OPERATION”

[ArsThaumaturgis]

(This text is partially copied from the forum, as this seems like the place for this issue, now that it's been confirmed to be a bug.)

In my current project, in order to support antialiasing, I render to an off-screen buffer that, depending on the game’s settings, may be set to be multisampled. If the player changes the relevant setting while the game is running, the relevant method is called, recreating the buffer and associating the camera with it.

I believe that this had previously worked.

However, as of a few days ago, I found that enabling multisampling resulted in an OpenGL error being reported. Adding " gl-debug #t" to my “prc” file (as suggested by the initial error message) resulted in this error-text being repeated:

:display:gsg:glgsg(error): GL_INVALID_OPERATION error generated. Depth formats do not match.

It seems that part of the issue is the number of depth-bits requested when constructing frame-buffer properties: if a 32 depth-bits are requested, the issue is present on my machine; when 16 depth-bits are requested, it isn't, I believe.

Below is a short test-program that displays the issue on my machine. Note the parameter to "makeBuffers", which controls the number of multi-samples requested, and the two calls to "setDepthBits", one of which is commented-out.

from direct.showbase import ShowBase as showBase
from panda3d.core import Vec4, NodePath, PandaNode, FrameBufferProperties, GraphicsPipe, GraphicsOutput, Texture

class game(showBase.ShowBase):

    def __init__(self):
        showBase.ShowBase.__init__(self)

        self.rootNode = NodePath(PandaNode("root"))

        self.model = loader.loadModel("panda")
        self.model.reparentTo(self.rootNode)
        self.model.setPos(0, 50, -5)

        self.mainBuffer = None
        self.sceneCamera = None
        self.sceneTexture = None

        self.card = base.win.getTextureCard()
        self.card.reparentTo(render2d)
        self.card.setShaderOff(1)

        self.makeBuffers(8)

    def makeBuffers(self, multisamples):
        frameProperties = FrameBufferProperties()
        frameProperties.setMultisamples(multisamples)
        frameProperties.setRgbaBits(8, 8, 8, 0)
        frameProperties.setDepthBits(32)
        #frameProperties.setDepthBits(16)

        windowProperties = base.win.getProperties()

        self.mainBuffer = base.graphicsEngine.makeOutput(base.pipe, "Main Buffer", -1,
                                                         frameProperties, windowProperties,
                                                         GraphicsPipe.BFRefuseWindow, base.win.getGsg(), base.win)

        if self.sceneCamera is None:
            self.sceneCamera = base.makeCamera(self.mainBuffer)
            self.sceneCamera.node().setScene(self.rootNode)
        else:
            region = self.mainBuffer.makeDisplayRegion(0, 1, 0, 1)
            region.setCamera(self.sceneCamera)

        self.sceneTexture = Texture()

        self.mainBuffer.addRenderTexture(self.sceneTexture,
                                         GraphicsOutput.RTMBindOrCopy)

        self.card.setTexture(self.sceneTexture)

app = game()
app.run()

[rdb]

I could reproduce this and I think this is fixed now. Let me know if you still run into issues.

[ArsThaumaturgis]

Having tried a new build, it does indeed seem to be fixed! Thank you very much! ^_^