//
// Copyright 2020 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 PXR_IMAGING_HGIGL_STATE_H
#define PXR_IMAGING_HGIGL_STATE_H

#include "pxr/pxr.h"
#include "pxr/imaging/hgiGL/api.h"


PXR_NAMESPACE_OPEN_SCOPE


/// \class HgiGLScopedStateHolder
///
/// OpenGL state guard object.
///
/// We've historically allowed applications to change global OpenGL. 
/// Consecutive code then relies on certain global state having been set.
/// This results in difficult to manage and inefficient OpenGL code.
///
/// For Hgi transition, we defensively capture state in this object and restore
/// it to the previous state to keep our applications function as before.
/// The end goal is to not need this object at all and make sure all opengl
/// state is only changed via HgiPipeline objects.
///
class HgiGL_ScopedStateHolder final
{
public:
    HGIGL_API
    HgiGL_ScopedStateHolder();

    HGIGL_API
    ~HgiGL_ScopedStateHolder();

private:
    HgiGL_ScopedStateHolder& operator=(const HgiGL_ScopedStateHolder&) = delete;
    HgiGL_ScopedStateHolder(const HgiGL_ScopedStateHolder&) = delete;

    int32_t _restoreDrawFramebuffer;
    int32_t _restoreReadFramebuffer;
    int32_t _restoreRenderBuffer;
    int32_t _restoreVao;
    bool _restoreDepthTest;
    bool _restoreDepthWriteMask;
    int32_t _restoreStencilWriteMask;
    int32_t _restoreDepthFunc;
    int32_t _restoreViewport[4];
    bool _restoreblendEnabled;
    int32_t _restoreColorOp;
    int32_t _restoreAlphaOp;
    int32_t _restoreColorSrcFnOp;
    int32_t _restoreAlphaSrcFnOp;
    int32_t _restoreColorDstFnOp;
    int32_t _restoreAlphaDstFnOp;
    bool _restoreAlphaToCoverage;
    float _lineWidth;
    bool _cullFace;
    int32_t _cullMode;
    bool _rasterizerDiscard;
};


PXR_NAMESPACE_CLOSE_SCOPE

#endif