glbuffers.cpp Example File
demos/boxes/glbuffers.cpp

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

 //============================================================================//
 //                                  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);
 }