- Qt 5.5
- Qt Widgets
- Boxes
- glbuffers.cpp Example File
- Qt 5.5.1 Reference Documentation

# glbuffers.cpp Example File

graphicsview/boxes/glbuffers.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the demonstration applications of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:LGPL21$
    ** Commercial License Usage
    ** Licensees holding valid commercial Qt licenses may use this file in
    ** accordance with the commercial license agreement provided with the
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    ** information use the contact form at http://www.qt.io/contact-us.
    **
    ** GNU Lesser General Public License Usage
    ** Alternatively, this file may be used under the terms of the GNU Lesser
    ** General Public License version 2.1 or version 3 as published by the Free
    ** Software Foundation and appearing in the file LICENSE.LGPLv21 and
    ** LICENSE.LGPLv3 included in the packaging of this file. Please review the
    ** following information to ensure the GNU Lesser General Public License
    ** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
    ** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
    **
    ** As a special exception, The Qt Company gives you certain additional
    ** rights. These rights are described in The Qt Company LGPL Exception
    ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
    **
    ** $QT_END_LICENSE$
    **
    ****************************************************************************/

    #include "glbuffers.h"
    #include <QtGui/qmatrix4x4.h>

    void qgluPerspective(GLdouble fovy, GLdouble aspect, GLdouble zNear, GLdouble zFar)
    {
        const GLdouble ymax = zNear * tan(fovy * M_PI / 360.0);
        const GLdouble ymin = -ymax;
        const GLdouble xmin = ymin * aspect;
        const GLdouble xmax = ymax * aspect;
        glFrustum(xmin, xmax, ymin, ymax, zNear, zFar);
    }

    //============================================================================//
    //                                  GLTexture                                 //
    //============================================================================//

    GLTexture::GLTexture() : m_texture(0), m_failed(false)
    {
        glGenTextures(1, &m_texture);
    }

    GLTexture::~GLTexture()
    {
        glDeleteTextures(1, &m_texture);
    }

    //============================================================================//
    //                                 GLTexture2D                                //
    //============================================================================//

    GLTexture2D::GLTexture2D(int width, int height)
    {
        glBindTexture(GL_TEXTURE_2D, m_texture);
        glTexImage2D(GL_TEXTURE_2D, 0, 4, width, height, 0,
            GL_BGRA, GL_UNSIGNED_BYTE, 0);

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        //glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
        //glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE);
        glBindTexture(GL_TEXTURE_2D, 0);
    }

    GLTexture2D::GLTexture2D(const QString& fileName, int width, int height)
    {
        // TODO: Add error handling.
        QImage image(fileName);

        if (image.isNull()) {
            m_failed = true;
            return;
        }

        image = image.convertToFormat(QImage::Format_ARGB32);

        //qDebug() << "Image size:" << image.width() << "x" << image.height();
        if (width <= 0)
            width = image.width();
        if (height <= 0)
            height = image.height();
        if (width != image.width() || height != image.height())
            image = image.scaled(width, height, Qt::IgnoreAspectRatio, Qt::SmoothTransformation);

        glBindTexture(GL_TEXTURE_2D, m_texture);

        // Works on x86, so probably works on all little-endian systems.
        // Does it work on big-endian systems?
        glTexImage2D(GL_TEXTURE_2D, 0, 4, image.width(), image.height(), 0,
            GL_BGRA, GL_UNSIGNED_BYTE, image.bits());

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        //glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
        //glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE);
        glBindTexture(GL_TEXTURE_2D, 0);
    }

    void GLTexture2D::load(int width, int height, QRgb *data)
    {
        glBindTexture(GL_TEXTURE_2D, m_texture);
        glTexImage2D(GL_TEXTURE_2D, 0, 4, width, height, 0,
            GL_BGRA, GL_UNSIGNED_BYTE, data);
        glBindTexture(GL_TEXTURE_2D, 0);
    }

    void GLTexture2D::bind()
    {
        glBindTexture(GL_TEXTURE_2D, m_texture);
        glEnable(GL_TEXTURE_2D);
    }

    void GLTexture2D::unbind()
    {
        glBindTexture(GL_TEXTURE_2D, 0);
        glDisable(GL_TEXTURE_2D);
    }

    //============================================================================//
    //                                 GLTexture3D                                //
    //============================================================================//

    GLTexture3D::GLTexture3D(int width, int height, int depth)
    {
        GLBUFFERS_ASSERT_OPENGL("GLTexture3D::GLTexture3D", glTexImage3D, return)

        glBindTexture(GL_TEXTURE_3D, m_texture);
        glTexImage3D(GL_TEXTURE_3D, 0, 4, width, height, depth, 0,
            GL_BGRA, GL_UNSIGNED_BYTE, 0);

        glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_S, GL_REPEAT);
        glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_T, GL_REPEAT);
        glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_R, GL_REPEAT);
        glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        //glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
        //glTexParameteri(GL_TEXTURE_3D, GL_GENERATE_MIPMAP, GL_TRUE);
        glBindTexture(GL_TEXTURE_3D, 0);
    }

    void GLTexture3D::load(int width, int height, int depth, QRgb *data)
    {
        GLBUFFERS_ASSERT_OPENGL("GLTexture3D::load", glTexImage3D, return)

        glBindTexture(GL_TEXTURE_3D, m_texture);
        glTexImage3D(GL_TEXTURE_3D, 0, 4, width, height, depth, 0,
            GL_BGRA, GL_UNSIGNED_BYTE, data);
        glBindTexture(GL_TEXTURE_3D, 0);
    }

    void GLTexture3D::bind()
    {
        glBindTexture(GL_TEXTURE_3D, m_texture);
        glEnable(GL_TEXTURE_3D);
    }

    void GLTexture3D::unbind()
    {
        glBindTexture(GL_TEXTURE_3D, 0);
        glDisable(GL_TEXTURE_3D);
    }

    //============================================================================//
    //                                GLTextureCube                               //
    //============================================================================//

    GLTextureCube::GLTextureCube(int size)
    {
        glBindTexture(GL_TEXTURE_CUBE_MAP, m_texture);

        for (int i = 0; i < 6; ++i)
            glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, 4, size, size, 0,
                GL_BGRA, GL_UNSIGNED_BYTE, 0);

        glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
        glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
        glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
        glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        //glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
        //glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_GENERATE_MIPMAP, GL_TRUE);
        glBindTexture(GL_TEXTURE_CUBE_MAP, 0);
    }

    GLTextureCube::GLTextureCube(const QStringList& fileNames, int size)
    {
        // TODO: Add error handling.

        glBindTexture(GL_TEXTURE_CUBE_MAP, m_texture);

        int index = 0;
        foreach (QString file, fileNames) {
            QImage image(file);
            if (image.isNull()) {
                m_failed = true;
                break;
            }

            image = image.convertToFormat(QImage::Format_ARGB32);

            //qDebug() << "Image size:" << image.width() << "x" << image.height();
            if (size <= 0)
                size = image.width();
            if (size != image.width() || size != image.height())
                image = image.scaled(size, size, Qt::IgnoreAspectRatio, Qt::SmoothTransformation);

            // Works on x86, so probably works on all little-endian systems.
            // Does it work on big-endian systems?
            glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + index, 0, 4, image.width(), image.height(), 0,
                GL_BGRA, GL_UNSIGNED_BYTE, image.bits());

            if (++index == 6)
                break;
        }

        // Clear remaining faces.
        while (index < 6) {
            glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + index, 0, 4, size, size, 0,
                GL_BGRA, GL_UNSIGNED_BYTE, 0);
            ++index;
        }

        glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
        glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
        glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
        glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        //glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
        //glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_GENERATE_MIPMAP, GL_TRUE);
        glBindTexture(GL_TEXTURE_CUBE_MAP, 0);
    }

    void GLTextureCube::load(int size, int face, QRgb *data)
    {
        glBindTexture(GL_TEXTURE_CUBE_MAP, m_texture);
            glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + face, 0, 4, size, size, 0,
                GL_BGRA, GL_UNSIGNED_BYTE, data);
        glBindTexture(GL_TEXTURE_CUBE_MAP, 0);
    }

    void GLTextureCube::bind()
    {
        glBindTexture(GL_TEXTURE_CUBE_MAP, m_texture);
        glEnable(GL_TEXTURE_CUBE_MAP);
    }

    void GLTextureCube::unbind()
    {
        glBindTexture(GL_TEXTURE_CUBE_MAP, 0);
        glDisable(GL_TEXTURE_CUBE_MAP);
    }

    //============================================================================//
    //                            GLFrameBufferObject                             //
    //============================================================================//

    GLFrameBufferObject::GLFrameBufferObject(int width, int height)
        : m_fbo(0)
        , m_depthBuffer(0)
        , m_width(width)
        , m_height(height)
        , m_failed(false)
    {
        GLBUFFERS_ASSERT_OPENGL("GLFrameBufferObject::GLFrameBufferObject",
            glGenFramebuffersEXT && glGenRenderbuffersEXT && glBindRenderbufferEXT && glRenderbufferStorageEXT, return)

        // TODO: share depth buffers of same size
        glGenFramebuffersEXT(1, &m_fbo);
        //glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, m_fbo);
        glGenRenderbuffersEXT(1, &m_depthBuffer);
        glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, m_depthBuffer);
        glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH_COMPONENT, m_width, m_height);
        //glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, m_depthBuffer);
        //glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
    }

    GLFrameBufferObject::~GLFrameBufferObject()
    {
        GLBUFFERS_ASSERT_OPENGL("GLFrameBufferObject::~GLFrameBufferObject",
            glDeleteFramebuffersEXT && glDeleteRenderbuffersEXT, return)

        glDeleteFramebuffersEXT(1, &m_fbo);
        glDeleteRenderbuffersEXT(1, &m_depthBuffer);
    }

    void GLFrameBufferObject::setAsRenderTarget(bool state)
    {
        GLBUFFERS_ASSERT_OPENGL("GLFrameBufferObject::setAsRenderTarget", glBindFramebufferEXT, return)

        if (state) {
            glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, m_fbo);
            glPushAttrib(GL_VIEWPORT_BIT);
            glViewport(0, 0, m_width, m_height);
        } else {
            glPopAttrib();
            glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
        }
    }

    bool GLFrameBufferObject::isComplete()
    {
        GLBUFFERS_ASSERT_OPENGL("GLFrameBufferObject::isComplete", glCheckFramebufferStatusEXT, return false)

        return GL_FRAMEBUFFER_COMPLETE_EXT == glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
    }

    //============================================================================//
    //                             GLRenderTargetCube                             //
    //============================================================================//

    GLRenderTargetCube::GLRenderTargetCube(int size)
        : GLTextureCube(size)
        , m_fbo(size, size)
    {
    }

    void GLRenderTargetCube::begin(int face)
    {
        GLBUFFERS_ASSERT_OPENGL("GLRenderTargetCube::begin",
            glFramebufferTexture2DEXT && glFramebufferRenderbufferEXT, return)

        m_fbo.setAsRenderTarget(true);
        glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,
            GL_TEXTURE_CUBE_MAP_POSITIVE_X + face, m_texture, 0);
        glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, m_fbo.m_depthBuffer);
    }

    void GLRenderTargetCube::end()
    {
        m_fbo.setAsRenderTarget(false);
    }

    void GLRenderTargetCube::getViewMatrix(QMatrix4x4& mat, int face)
    {
        if (face < 0 || face >= 6) {
            qWarning("GLRenderTargetCube::getViewMatrix: 'face' must be in the range [0, 6). (face == %d)", face);
            return;
        }

        static int perm[6][3] = {
            {2, 1, 0},
            {2, 1, 0},
            {0, 2, 1},
            {0, 2, 1},
            {0, 1, 2},
            {0, 1, 2},
        };

        static float signs[6][3] = {
            {-1.0f, -1.0f, -1.0f},
            {+1.0f, -1.0f, +1.0f},
            {+1.0f, +1.0f, -1.0f},
            {+1.0f, -1.0f, +1.0f},
            {+1.0f, -1.0f, -1.0f},
            {-1.0f, -1.0f, +1.0f},
        };

        mat.fill(0.0f);
        for (int i = 0; i < 3; ++i)
            mat(i, perm[face][i]) = signs[face][i];
        mat(3, 3) = 1.0f;
    }

    void GLRenderTargetCube::getProjectionMatrix(QMatrix4x4& mat, float nearZ, float farZ)
    {
        static const QMatrix4x4 reference(
                1.0f, 0.0f, 0.0f, 0.0f,
                0.0f, 1.0f, 0.0f, 0.0f,
                0.0f, 0.0f, 0.0f, 0.0f,
                0.0f, 0.0f, -1.0f, 0.0f);

        mat = reference;
        mat(2, 2) = (nearZ+farZ)/(nearZ-farZ);
        mat(2, 3) = 2.0f*nearZ*farZ/(nearZ-farZ);
    }