magnum/doc/snippets/MeshTools-gl.cpp

/*
    This file is part of Magnum.

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

    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 <utility> /* std::move() in a snippet */
#include <Corrade/Containers/Pair.h>
#include <Corrade/Containers/StridedArrayView.h>

#include "Magnum/GL/AbstractShaderProgram.h"
#include "Magnum/GL/Buffer.h"
#include "Magnum/GL/Mesh.h"
#include "Magnum/GL/MeshView.h"
#include "Magnum/Math/Color.h"
#include "Magnum/MeshTools/Compile.h"
#include "Magnum/MeshTools/CompressIndices.h"
#include "Magnum/MeshTools/Concatenate.h"
#include "Magnum/MeshTools/Interleave.h"
#include "Magnum/Trade/MeshData.h"

#ifdef MAGNUM_BUILD_DEPRECATED
#include <tuple>
#include <vector>
#endif

#define DOXYGEN_ELLIPSIS(...) __VA_ARGS__

using namespace Magnum;
using namespace Magnum::Math::Literals;

/* Make sure the name doesn't conflict with any other snippets to avoid linker
   warnings, unlike with `int main()` there now has to be a declaration to
   avoid -Wmisssing-prototypes */
void mainMeshToolsGL();
void mainMeshToolsGL() {
{
struct MyShader: GL::AbstractShaderProgram {
    MyShader& setColor(const Color3&) {
        return *this;
    }
    MyShader& draw(GL::MeshView& mesh) {
        GL::AbstractShaderProgram::draw(mesh);
        return *this;
    }
} shader;
/* [meshtools-concatenate] */
Trade::MeshData sphere = DOXYGEN_ELLIPSIS(Trade::MeshData{{}, 0});
Trade::MeshData cube = DOXYGEN_ELLIPSIS(Trade::MeshData{{}, 0});
Trade::MeshData cylinder = DOXYGEN_ELLIPSIS(Trade::MeshData{{}, 0});
Trade::MeshData primitives = MeshTools::concatenate({sphere, cube, cylinder});

GL::Mesh mesh = MeshTools::compile(primitives);
/* [meshtools-concatenate] */

/* [meshtools-concatenate-offsets] */
GL::MeshView meshSphereView{mesh},
    meshCubeView{mesh},
    meshCylinderView{mesh};
meshSphereView
    .setIndexOffset(0)
    .setCount(sphere.indexCount());
meshCubeView
    .setIndexOffset(meshSphereView.indexOffset() + meshSphereView.count())
    .setCount(cube.indexCount());
meshCylinderView
    .setIndexOffset(meshCubeView.indexOffset() + meshCubeView.count())
    .setCount(cylinder.indexCount());
shader
    .setColor(0x2f83cc_rgbf)
    .draw(meshSphereView)
    .setColor(0x3bd267_rgbf)
    .draw(meshCubeView)
    .setColor(0xc7cf2f_rgbf)
    .draw(meshCylinderView);
/* [meshtools-concatenate-offsets] */
}

{
Trade::MeshData meshData{MeshPrimitive::Lines, 5};
/* [compile-external] */
GL::Buffer indices{meshData.indexData()};
GL::Buffer vertices{meshData.vertexData()};
GL::Mesh mesh = MeshTools::compile(meshData, indices, vertices);
/* [compile-external] */
}

{
Trade::MeshData meshData{MeshPrimitive::Lines, 5};
/* [compile-external-attributes] */
struct MyShader: GL::AbstractShaderProgram {
    typedef GL::Attribute<DOXYGEN_ELLIPSIS(7, Vector2)> MyCustomAttribute;

    DOXYGEN_ELLIPSIS()
};
Trade::MeshAttribute myCustomAttribute = DOXYGEN_ELLIPSIS({});

GL::Buffer indices{meshData.indexData()};
GL::Buffer vertices{meshData.vertexData()};

/* Let compile() handle the usual attributes and configure custom ones after */
GL::Mesh mesh = MeshTools::compile(meshData, std::move(indices), vertices);
mesh.addVertexBuffer(std::move(vertices),
    meshData.attributeOffset(myCustomAttribute),
    meshData.attributeStride(myCustomAttribute),
    GL::DynamicAttribute{
        MyShader::MyCustomAttribute{},
        meshData.attributeFormat(myCustomAttribute)
    });
/* [compile-external-attributes] */
}

{
/* [compressIndices] */
Containers::Array<UnsignedInt> indices;

Containers::Pair<Containers::Array<char>, MeshIndexType> compressed =
    MeshTools::compressIndices(indices);

GL::Buffer indexBuffer;
indexBuffer.setData(compressed.first());

GL::Mesh mesh;
mesh.setCount(indices.size())
    .setIndexBuffer(indexBuffer, 0, compressed.second());
/* [compressIndices] */
}

#ifdef MAGNUM_BUILD_DEPRECATED
{
CORRADE_IGNORE_DEPRECATED_PUSH
/* [compressIndices-stl] */
std::vector<UnsignedInt> indices;

Containers::Array<char> indexData;
MeshIndexType indexType;
UnsignedInt indexStart, indexEnd;
std::tie(indexData, indexType, indexStart, indexEnd) =
    MeshTools::compressIndices(indices);

GL::Buffer indexBuffer;
indexBuffer.setData(indexData, GL::BufferUsage::StaticDraw);

GL::Mesh mesh;
mesh.setCount(indices.size())
    .setIndexBuffer(indexBuffer, 0, indexType, indexStart, indexEnd);
/* [compressIndices-stl] */
}
CORRADE_IGNORE_DEPRECATED_POP
#endif

{
struct MyShader {
    typedef GL::Attribute<0, Vector3> Position;
    typedef GL::Attribute<0, Vector2> TextureCoordinates;
};
/* [interleave1] */
Containers::ArrayView<const Vector3> positions;
Containers::ArrayView<const Vector2> textureCoordinates;

GL::Buffer vertexBuffer;
vertexBuffer.setData(MeshTools::interleave(positions, textureCoordinates));

GL::Mesh mesh;
mesh.setCount(positions.size())
    .addVertexBuffer(vertexBuffer, 0, MyShader::Position{},
                                      MyShader::TextureCoordinates{});
/* [interleave1] */
}

}