visualizeAovTask.h

//
// Copyright 2021 Pixar
//
// Licensed under the Apache License, Version 2.0 (the "Apache License")
// with the following modification; you may not use this file except in
// compliance with the Apache License and the following modification to it:
// Section 6. Trademarks. is deleted and replaced with:
//
// 6. Trademarks. This License does not grant permission to use the trade
//    names, trademarks, service marks, or product names of the Licensor
//    and its affiliates, except as required to comply with Section 4(c) of
//    the License and to reproduce the content of the NOTICE file.
//
// You may obtain a copy of the Apache License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the Apache License with the above modification is
// distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the Apache License for the specific
// language governing permissions and limitations under the Apache License.
//
#ifndef HDX_VISUALIZE_AOV_TASK_H
#define HDX_VISUALIZE_AOV_TASK_H

#include "pxr/pxr.h"
#include "pxr/base/gf/vec3i.h"
#include "pxr/imaging/hdx/api.h"
#include "pxr/imaging/hdx/task.h"
#include "pxr/imaging/hdx/tokens.h"
#include "pxr/imaging/hgi/attachmentDesc.h"
#include "pxr/imaging/hgi/buffer.h"
#include "pxr/imaging/hgi/graphicsPipeline.h"
#include "pxr/imaging/hgi/resourceBindings.h"
#include "pxr/imaging/hgi/shaderProgram.h"
#include "pxr/imaging/hgi/texture.h"
#include "pxr/usd/sdf/path.h"

PXR_NAMESPACE_OPEN_SCOPE

class HdxVisualizeAovTask : public HdxTask
{
public:
    HDX_API
    HdxVisualizeAovTask(HdSceneDelegate* delegate, SdfPath const& id);

    HDX_API
    ~HdxVisualizeAovTask() override;

    HDX_API
    void Prepare(HdTaskContext* ctx,
                 HdRenderIndex* renderIndex) override;

    HDX_API
    void Execute(HdTaskContext* ctx) override;

protected:
    HDX_API
    void _Sync(HdSceneDelegate* delegate,
               HdTaskContext* ctx,
               HdDirtyBits* dirtyBits) override;

private:
    // Enumeration of visualization kernels
    enum VizKernel {
        VizKernelDepth = 0,
        VizKernelId,
        VizKernelNormal,
        VizKernelFallback,
        VizKernelNone
    };

    HdxVisualizeAovTask() = delete;
    HdxVisualizeAovTask(const HdxVisualizeAovTask &) = delete;
    HdxVisualizeAovTask &operator =(const HdxVisualizeAovTask &) = delete;

    // Returns true if the enum member was updated, indicating that the kernel
    // to be used has changed.
    bool _UpdateVizKernel(TfToken const &aovName);

    // Returns a token used in sampling the texture based on the kernel used.
    TfToken const& _GetTextureIdentifierForShader() const;

    // Returns the fragment shader mixin based on the kernel used.
    TfToken const& _GetFragmentMixin() const;

    // ------------- Hgi resource creation/deletion utilities ------------------
    // Utility function to create the GL program for color correction
    bool _CreateShaderResources(HgiTextureDesc const& inputAovTextureDesc);

    // Utility function to create buffer resources.
    bool _CreateBufferResources();

    // Utility to create resource bindings
    bool _CreateResourceBindings(HgiTextureHandle const& inputAovTexture);

    // Utility to create a pipeline
    bool _CreatePipeline(HgiTextureDesc const& outputTextureDesc);

    // Utility to create a texture sampler
    bool _CreateSampler();

    // Create texture to write the colorized results into.
    bool _CreateOutputTexture(GfVec3i const &dimensions);

    // Destroy shader program and the shader functions it holds.
    void _DestroyShaderProgram();

    // Print shader compile errors.
    void _PrintCompileErrors();
    // -------------------------------------------------------------------------
    
    // Readback the depth AOV on the CPU to update min, max values.
    void _UpdateMinMaxDepth(HgiTextureHandle const &inputAovTexture);

    // Execute the appropriate kernel and update the task context 'color' entry.
    void _ApplyVisualizationKernel(HgiTextureHandle const& outputTexture);

    // Kernel dependent resources
    HgiTextureHandle _outputTexture;
    GfVec3i _outputTextureDimensions;
    HgiAttachmentDesc _outputAttachmentDesc;
    HgiShaderProgramHandle _shaderProgram;
    HgiResourceBindingsHandle _resourceBindings;
    HgiGraphicsPipelineHandle _pipeline;

    // Kernel independent resources
    HgiBufferHandle _indexBuffer;
    HgiBufferHandle _vertexBuffer;
    HgiSamplerHandle _sampler;

    float _screenSize[2];
    float _minMaxDepth[2];
    VizKernel _vizKernel;
};


struct HdxVisualizeAovTaskParams
{
    HDX_API
    HdxVisualizeAovTaskParams();

    TfToken aovName;
};

// VtValue requirements
HDX_API
std::ostream& operator<<(std::ostream& out, const HdxVisualizeAovTaskParams& pv);
HDX_API
bool operator==(const HdxVisualizeAovTaskParams& lhs,
                const HdxVisualizeAovTaskParams& rhs);
HDX_API
bool operator!=(const HdxVisualizeAovTaskParams& lhs,
                const HdxVisualizeAovTaskParams& rhs);

PXR_NAMESPACE_CLOSE_SCOPE

#endif