StateSetManipulator Implementation

[tmonk22]

Hi, the scene graph contains N nodes, and I want to switch the POLYGON_MODE of all nodes. How can I do it? One way is to recreate a pipeline for each node, but nodes will be added or removed dynamically. It feels very troublesome. There is this class StateSetManipulator in osg that can achieve this. I looked at it and it only changed the State of the top-level Camera in the Viewer.

[tmonk22]

code:
while (viewer->advanceToNextFrame())
{
if ((++frameCount % 500) == 0)
{
viewer->deviceWaitIdle();
struct SetPipelineStates : public vsg::Visitor
{
void apply(vsg::Object& obj)
{
//std::cout << "apply " << obj.className() << std::endl;
obj.traverse(*this);
}
void apply(vsg::BindGraphicsPipeline& bgp)
{
for (auto& it : bgp.pipeline->pipelineStates)
{
it->accept(*this);
}
}
void apply(vsg::RasterizationState& rs)
{
rs.polygonMode = (VkPolygonMode)((rs.polygonMode+1)%3);
}
};

        SetPipelineStates setPipelineStates;
        sceneGraph->accept(setPipelineStates);
        auto result = viewer->compileManager->compile(sceneGraph);
        assert(result.result == VK_SUCCESS);
        vsg::updateViewer(*viewer, result);
    }

    viewer->handleEvents();
    viewer->update();
    viewer->recordAndSubmit();
    viewer->present();
}

When I do this, the displayed result does not change, only when the width and height of the window change, the displayed result is correct.

[robertosfield]

On my phone right now so just a quick reply - have a look at the vsgdynamicstate example.

…

On Thu, 12 Jun 2025, 07:52 couchpotato, ***@***.***> wrote: code: while (viewer->advanceToNextFrame()) { if ((++frameCount % 500) == 0) { viewer->deviceWaitIdle(); struct SetPipelineStates : public vsg::Visitor { void apply(vsg::Object& obj) { //std::cout << "apply " << obj.className() << std::endl; obj.traverse(*this); } void apply(vsg::BindGraphicsPipeline& bgp) { for (auto& it : bgp.pipeline->pipelineStates) { it->accept(*this); } } void apply(vsg::RasterizationState& rs) { rs.polygonMode = (VkPolygonMode)((rs.polygonMode+1)%3); } }; SetPipelineStates setPipelineStates; sceneGraph->accept(setPipelineStates); auto result = viewer->compileManager->compile(sceneGraph); assert(result.result == VK_SUCCESS); vsg::updateViewer(*viewer, result); } viewer->handleEvents(); viewer->update(); viewer->recordAndSubmit(); viewer->present(); } When I do this, the displayed result does not change, only when the width and height of the window change, the displayed result is correct. — Reply to this email directly, view it on GitHub <#1493 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAKEGUFLU7RS3ZC2YF6CUY33DEPRHAVCNFSM6AAAAAB7EDZI6KVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTGNBUGIZDOMA> . You are receiving this because you are subscribed to this thread.Message ID: <vsg-dev/VulkanSceneGraph/repo-discussions/1493/comments/13442270@ github.com>

[tmonk22]

Do you mean to add DynamicState (VK_DYNAMIC_STATE_POLYGON_MODE_EXT) to pipelineStates in StateGroup? I can add it to the graphics pipeline I created, but does the vsg::node returned by vsg::read_cast contain the dynamicState?

[tmonk22]

class SetPolygonMode : public vsg::Inherit<vsg::Command, SetPolygonMode> { public: void record(vsg::CommandBuffer& commandBuffer) const override { //vkCmdSetLineWidth(commandBuffer, 0.1); vkCmdSetPolygonModeEXT(0, polygonMode); } VkPolygonMode polygonMode = VkPolygonMode::VK_POLYGON_MODE_FILL; };
Is this true? Compilation fails with error LNK2019: unresolved external symbol vkCmdSetPolygonModeEXT but compiles successfully with vkCmdSetLineWidth

[tmonk22]

class SetPolygonMode : public vsg::Inherit<vsg::Command, SetPolygonMode>
{
public:
    void record(vsg::CommandBuffer& commandBuffer) const override
    {
        typedef void(VKAPI_PTR * PFN_vkCmdSetPolygonModeEXT)(VkCommandBuffer, VkPolygonMode);

        auto device = commandBuffer.getDevice();
        PFN_vkCmdSetPolygonModeEXT fpCmdSetPolygonModeEXT =
            (PFN_vkCmdSetPolygonModeEXT)vkGetDeviceProcAddr(*device, "vkCmdSetPolygonModeEXT");

        if (fpCmdSetPolygonModeEXT)
        {
            fpCmdSetPolygonModeEXT(commandBuffer, polygonMode);
        }

        // 调用函数
        
        //vkCmdSetLineWidth(commandBuffer, 0.1);
        //vkCmdSetPolygonModeEXT(0, polygonMode);
    }
    VkPolygonMode polygonMode = VkPolygonMode::VK_POLYGON_MODE_FILL;
};

but fpCmdSetPolygonModeEXT is nullptr 。How should I do to achieve this function? Thanks！

[robertosfield]

I'm afraid I'm too busy right now to dive deep into a topic and I have a lot of work to get completed. This area is one that OpenGL is much easier to manage state than Vulkan so it's a bit more awkward as Vulkan is written with static state as it's foundation, as you are are finding out sometimes requires extensions to get the extra control you need.

From a quick review it looks like you are on the right track. The VSG could do with vsg::SetPolygonMode implementation and what you've written on first pass looks generally the right thing to do. Not all drivers will support this extension so have a look at what extensions are supported using a tool like vkinfo or the 'vsgdeviceselection --extensions' example.

You'll need to pass the DynamicState settings to the loader as custom ShaderSet so that the loaders know to use it. The vsgshadow example has that sets the ShaderSet::defaultGraphicsPipelineStates to inject a pipeline state, not exactly what you want but might help point you in the right direction.

[tmonk22]

part1
class SetPolygonModeCommand : public vsg::Inherit<vsg::Command, SetPolygonModeCommand>
{
public:
    void record(vsg::CommandBuffer& commandBuffer) const override
    {
        auto func = reinterpret_cast<PFN_vkCmdSetPolygonModeEXT>(
            vkGetDeviceProcAddr(*commandBuffer.getDevice(), "vkCmdSetPolygonModeEXT"));
        if (func)
        {
            func(commandBuffer, polygonMode);
        }
        else
        {
            std::cerr << "vkCmdSetPolygonModeEXT not loaded!\n";
        }
    }

    VkPolygonMode polygonMode;
};

part2
windowTraits->deviceExtensionNames.push_back(VK_EXT_EXTENDED_DYNAMIC_STATE_3_EXTENSION_NAME);

part3
 auto dynamicState = vsg::DynamicState::create();
dynamicState->dynamicStates.emplace_back(VK_DYNAMIC_STATE_LINE_WIDTH);
dynamicState->dynamicStates.emplace_back(VK_DYNAMIC_STATE_POLYGON_MODE_EXT);
   //gpConf->pipelineStates.push_back(dynamicState);

Thank you for your ideas. I have implemented it in this way, but I have a few questions. If you can answer them, I will be very grateful.

1. In part 3, after I blocked it, the function is normal. Is it necessary to configure it?
2. In the above text, I dynamically changed vsg::RasterizationState.polygonMode through visit. When the window size changes, the display result is correct. Why is this?
3. If I need to add some functions, such as highlighting, can I change the shader through the visit pipeline and then compile? Or do I have to create a new pipeline?

[AnyOldName3]

In the above text, I dynamically changed vsg::RasterizationState.polygonMode through visit. When the window size changes, the display result is correct. Why is this?

If you're not using dynamic viewport state, then the VSG needs to recreate all pipelines whenever the window size changes. When it does, it'll include any other changes you've made.

[tmonk22]

Thank you. If I change some status through visit and I don't want the window size to change, is there a way to make the status change pipeline effective again?
I have another question. In osg, I can adjust some properties of the parent node's StateSet to let it overwrite all child nodes, such as highlighting operations. How should I do this in vsg?

[AnyOldName3]

Thank you. If I change some status through visit and I don't want the window size to change, is there a way to make the status change pipeline effective again?

You'll need to apply a visitor that releases the existing compiled pipeline and recompiles it. Take a look at UpdateGraphicsPipelines in src\vsg\app\WindowResizeHandler.cpp for an example. If you don't release the existing one, and just redo the compile traversal, then it won't notice that the existing pipelines are stale.

I have another question. In osg, I can adjust some properties of the parent node's StateSet to let it overwrite all child nodes, such as highlighting operations. How should I do this in vsg?

If it's state that's baked into the pipeline, then the closest equivalent would be to do something that makes a different pipeline get used, e.g. having one vsg::View that sees the state one way and another that sees it a different way, or using a vsg::StateSwitch.

If it's dynamic state, then you can just put the command that binds it higher in the scenegraph just like a state attribute with OSG.

[tmonk22]

I think I understand. Thank you very much.