magnum/src/Magnum/GL/TransformFeedback.cpp

/*
    This file is part of Magnum.

    Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019,
                2020, 2021, 2022, 2023, 2024, 2025, 2026
              Vladimír Vondruš <mosra@centrum.cz>
    Copyright @ 2022 Hugo Amiard <hugo.amiard@wonderlandengine.com>

    Permission is hereby granted, free of charge, to any person obtaining a
    copy of this software and associated documentation files (the "Software"),
    to deal in the Software without restriction, including without limitation
    the rights to use, copy, modify, merge, publish, distribute, sublicense,
    and/or sell copies of the Software, and to permit persons to whom the
    Software is furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included
    in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
    DEALINGS IN THE SOFTWARE.
*/

#include "TransformFeedback.h"

#ifndef MAGNUM_TARGET_GLES2
#ifndef MAGNUM_TARGET_WEBGL
#include <Corrade/Containers/String.h>
#endif
#include <Corrade/Containers/Triple.h>
#include <Corrade/Utility/Assert.h>

#include "Magnum/GL/AbstractShaderProgram.h"
#include "Magnum/GL/Buffer.h"
#include "Magnum/GL/Context.h"
#include "Magnum/GL/Extensions.h"
#ifndef MAGNUM_TARGET_WEBGL
#include "Magnum/GL/Implementation/DebugState.h"
#endif
#include "Magnum/GL/Implementation/State.h"
#include "Magnum/GL/Implementation/TransformFeedbackState.h"

namespace Magnum { namespace GL {

Int TransformFeedback::maxInterleavedComponents() {
    #ifndef MAGNUM_TARGET_GLES
    if(!Context::current().isExtensionSupported<Extensions::EXT::transform_feedback>())
        return 0;
    #endif

    GLint& value = Context::current().state().transformFeedback.maxInterleavedComponents;

    if(value == 0)
        glGetIntegerv(GL_MAX_TRANSFORM_FEEDBACK_INTERLEAVED_COMPONENTS, &value);

    return value;
}

Int TransformFeedback::maxSeparateAttributes() {
    #ifndef MAGNUM_TARGET_GLES
    if(!Context::current().isExtensionSupported<Extensions::EXT::transform_feedback>())
        return 0;
    #endif

    GLint& value = Context::current().state().transformFeedback.maxSeparateAttributes;

    if(value == 0)
        glGetIntegerv(GL_MAX_TRANSFORM_FEEDBACK_SEPARATE_ATTRIBS, &value);

    return value;
}

Int TransformFeedback::maxSeparateComponents() {
    #ifndef MAGNUM_TARGET_GLES
    if(!Context::current().isExtensionSupported<Extensions::EXT::transform_feedback>())
        return 0;
    #endif

    GLint& value = Context::current().state().transformFeedback.maxSeparateComponents;

    if(value == 0)
        glGetIntegerv(GL_MAX_TRANSFORM_FEEDBACK_SEPARATE_COMPONENTS, &value);

    return value;
}

#ifndef MAGNUM_TARGET_GLES
Int TransformFeedback::maxBuffers() {
    if(!Context::current().isExtensionSupported<Extensions::ARB::transform_feedback3>())
        return maxSeparateAttributes();

    GLint& value = Context::current().state().transformFeedback.maxBuffers;

    if(value == 0)
        glGetIntegerv(GL_MAX_TRANSFORM_FEEDBACK_BUFFERS, &value);

    return value;
}

Int TransformFeedback::maxVertexStreams() {
    if(!Context::current().isExtensionSupported<Extensions::ARB::transform_feedback3>())
        return 1;

    GLint& value = Context::current().state().transformFeedback.maxVertexStreams;

    if(value == 0)
        glGetIntegerv(GL_MAX_VERTEX_STREAMS, &value);

    return value;
}
#endif

TransformFeedback::TransformFeedback(): _flags{ObjectFlag::DeleteOnDestruction} {
    Context::current().state().transformFeedback.createImplementation(*this);
    CORRADE_INTERNAL_ASSERT(_id != Implementation::State::DisengagedBinding);
}

void TransformFeedback::createImplementationDefault(TransformFeedback& self) {
    glGenTransformFeedbacks(1, &self._id);
}

#ifndef MAGNUM_TARGET_GLES
void TransformFeedback::createImplementationDSA(TransformFeedback& self) {
    glCreateTransformFeedbacks(1, &self._id);
    self._flags |= ObjectFlag::Created;
}
#endif

TransformFeedback::~TransformFeedback() {
    /* Moved out or not deleting on destruction, nothing to do */
    if(!_id || !(_flags & ObjectFlag::DeleteOnDestruction))
        return;

    /* If bound, remove itself from state */
    GLuint& binding = Context::current().state().transformFeedback.binding;
    if(binding == _id) binding = 0;

    glDeleteTransformFeedbacks(1, &_id);
}

void TransformFeedback::bindInternal() {
    GLuint& bound = Context::current().state().transformFeedback.binding;

    /* Already bound, nothing to do */
    if(bound == _id)
        return;

    /* Bind the transform feedback otherwise, which will also finally create it */
    bound = _id;
    _flags |= ObjectFlag::Created;
    glBindTransformFeedback(GL_TRANSFORM_FEEDBACK, _id);
}

#ifndef MAGNUM_TARGET_WEBGL
inline void TransformFeedback::createIfNotAlready() {
    if(_flags & ObjectFlag::Created)
        return;

    /* glGen*() does not create the object, just reserves the name. Some
       commands (such as glObjectLabel()) operate with IDs directly and they
       require the object to be created. Binding the transform feedback finally
       creates it. Also all EXT DSA functions implicitly create it. */
    bindInternal();

    /* In some cases, such as when this function is called on a object created
       using wrap(), ObjectFlag::Created might not be set but bindInternal()
       above was a no-op as the object was already bound somewhere. In that
       case assume that, since it's bound, it's already created, and we just
       didn't know. See the wrapCreateIfNotAlready() test for a repro case.

       Note that the branch is done this way instead of an unconditional |= to
       make code coverage report that this codepath is indeed tested. */
    if(!(_flags >= ObjectFlag::Created))
        _flags |= ObjectFlag::Created;
}
#endif

#ifndef MAGNUM_TARGET_WEBGL
Containers::String TransformFeedback::label() {
    createIfNotAlready();
    return Context::current().state().debug.getLabelImplementation(GL_TRANSFORM_FEEDBACK, _id);
}

TransformFeedback& TransformFeedback::setLabel(const Containers::StringView label) {
    createIfNotAlready();
    Context::current().state().debug.labelImplementation(GL_TRANSFORM_FEEDBACK, _id, label);
    return *this;
}
#endif

TransformFeedback& TransformFeedback::attachBuffer(const UnsignedInt index, Buffer& buffer, const GLintptr offset, const GLsizeiptr size) {
    Context::current().state().transformFeedback.attachRangeImplementation(*this, index, buffer, offset, size);
    return *this;
}

TransformFeedback& TransformFeedback::attachBuffer(const UnsignedInt index, Buffer& buffer) {
    Context::current().state().transformFeedback.attachBaseImplementation(*this, index, buffer);
    return *this;
}

void TransformFeedback::attachImplementationFallback(TransformFeedback& self, const GLuint index, Buffer& buffer, const GLintptr offset, const GLsizeiptr size) {
    self.bindInternal();
    buffer.bind(Buffer::Target(GL_TRANSFORM_FEEDBACK_BUFFER), index, offset, size);
}

#ifndef MAGNUM_TARGET_GLES
void TransformFeedback::attachImplementationDSA(TransformFeedback& self, const GLuint index, Buffer& buffer, const GLintptr offset, const GLsizeiptr size) {
    glTransformFeedbackBufferRange(self._id, index, buffer.id(), offset, size);
}
#endif

void TransformFeedback::attachImplementationFallback(TransformFeedback& self, const GLuint index, Buffer& buffer) {
    self.bindInternal();
    buffer.bind(Buffer::Target(GL_TRANSFORM_FEEDBACK_BUFFER), index);
}

#ifndef MAGNUM_TARGET_GLES
void TransformFeedback::attachImplementationDSA(TransformFeedback& self, const GLuint index, Buffer& buffer) {
    glTransformFeedbackBufferBase(self._id, index, buffer.id());
}
#endif

TransformFeedback& TransformFeedback::attachBuffers(const UnsignedInt firstIndex, Containers::ArrayView<const Containers::Triple<Buffer*, GLintptr, GLsizeiptr>> buffers) {
    Context::current().state().transformFeedback.attachRangesImplementation(*this, firstIndex, buffers);
    return *this;
}

TransformFeedback& TransformFeedback::attachBuffers(const UnsignedInt firstIndex, std::initializer_list<Containers::Triple<Buffer*, GLintptr, GLsizeiptr>> buffers) {
    Context::current().state().transformFeedback.attachRangesImplementation(*this, firstIndex, Containers::arrayView(buffers));
    return *this;
}

TransformFeedback& TransformFeedback::attachBuffers(const UnsignedInt firstIndex, Containers::ArrayView<Buffer* const> buffers) {
    Context::current().state().transformFeedback.attachBasesImplementation(*this, firstIndex, buffers);
    return *this;
}

TransformFeedback& TransformFeedback::attachBuffers(const UnsignedInt firstIndex, const std::initializer_list<Buffer*> buffers) {
    return attachBuffers(firstIndex, Containers::arrayView(buffers));
}

void TransformFeedback::attachImplementationFallback(TransformFeedback& self, const GLuint firstIndex, Containers::ArrayView<const Containers::Triple<Buffer*, GLintptr, GLsizeiptr>> buffers) {
    self.bindInternal();
    Buffer::bind(Buffer::Target(GL_TRANSFORM_FEEDBACK_BUFFER), firstIndex, buffers);
}

#ifndef MAGNUM_TARGET_GLES
void TransformFeedback::attachImplementationDSA(TransformFeedback& self, const GLuint firstIndex, Containers::ArrayView<const Containers::Triple<Buffer*, GLintptr, GLsizeiptr>> buffers) {
    for(std::size_t i = 0; i != buffers.size(); ++i) {
        Buffer* buffer = buffers[i].first();
        glTransformFeedbackBufferRange(self._id, firstIndex + i, buffer ? buffer->id() : 0, buffers[i].second(), buffers[i].third());
    }
}
#endif

void TransformFeedback::attachImplementationFallback(TransformFeedback& self, const GLuint firstIndex, Containers::ArrayView<Buffer* const> buffers) {
    self.bindInternal();
    Buffer::bind(Buffer::Target(GL_TRANSFORM_FEEDBACK_BUFFER), firstIndex, buffers);
}

#ifndef MAGNUM_TARGET_GLES
void TransformFeedback::attachImplementationDSA(TransformFeedback& self, const GLuint firstIndex, Containers::ArrayView<Buffer* const> buffers) {
    for(std::size_t i = 0; i != buffers.size(); ++i)
        glTransformFeedbackBufferBase(self._id, firstIndex + i, *(buffers.begin() + i) ? (*(buffers.begin() + i))->id() : 0);
}
#endif

void TransformFeedback::begin(AbstractShaderProgram& shader, const PrimitiveMode mode) {
    shader.use();
    bindInternal();
    glBeginTransformFeedback(GLenum(mode));
}

void TransformFeedback::pause() {
    bindInternal();
    glPauseTransformFeedback();
}

void TransformFeedback::resume() {
    bindInternal();
    glResumeTransformFeedback();
}

void TransformFeedback::end() {
    bindInternal();
    glEndTransformFeedback();
}

}}
#endif