glutils_funcs.cpp

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/*
    KWin - the KDE window manager
    This file is part of the KDE project.
 
    SPDX-FileCopyrightText: 2007 Rivo Laks <rivolaks@hot.ee>
 
    SPDX-License-Identifier: GPL-2.0-or-later
*/
 
#include "opengl/glplatform.h"
#include "opengl/glutils.h"
 
// Resolves given function, using getProcAddress
// Useful when functionality is defined in an extension with a different name
#define GL_RESOLVE_WITH_EXT(function, symbolName) \
    function = (function##_func)resolveFunction(#symbolName);
 
namespace KWin
{
 
static GLenum GetGraphicsResetStatus();
static void ReadnPixels(GLint x, GLint y, GLsizei width, GLsizei height, GLenum format,
                        GLenum type, GLsizei bufSize, GLvoid *data);
static void GetnUniformfv(GLuint program, GLint location, GLsizei bufSize, GLfloat *params);
 
// GL_ARB_robustness / GL_EXT_robustness
glGetGraphicsResetStatus_func glGetGraphicsResetStatus;
glReadnPixels_func glReadnPixels;
glGetnUniformfv_func glGetnUniformfv;
 
void glResolveFunctions(const std::function<resolveFuncPtr(const char *)> &resolveFunction)
{
    const bool haveArbRobustness = hasGLExtension(QByteArrayLiteral("GL_ARB_robustness"));
    const bool haveExtRobustness = hasGLExtension(QByteArrayLiteral("GL_EXT_robustness"));
    bool robustContext = false;
    if (GLPlatform::instance()->isGLES()) {
        if (haveExtRobustness) {
            GLint value = 0;
            glGetIntegerv(GL_CONTEXT_ROBUST_ACCESS_EXT, &value);
            robustContext = (value != 0);
        }
    } else {
        if (haveArbRobustness) {
            if (hasGLVersion(3, 0)) {
                GLint value = 0;
                glGetIntegerv(GL_CONTEXT_FLAGS, &value);
                if (value & GL_CONTEXT_FLAG_ROBUST_ACCESS_BIT_ARB) {
                    robustContext = true;
                }
            } else {
                robustContext = true;
            }
        }
    }
    if (robustContext && haveArbRobustness) {
        // See https://www.opengl.org/registry/specs/ARB/robustness.txt
        GL_RESOLVE_WITH_EXT(glGetGraphicsResetStatus, glGetGraphicsResetStatusARB);
        GL_RESOLVE_WITH_EXT(glReadnPixels, glReadnPixelsARB);
        GL_RESOLVE_WITH_EXT(glGetnUniformfv, glGetnUniformfvARB);
    } else if (robustContext && haveExtRobustness) {
        // See https://www.khronos.org/registry/gles/extensions/EXT/EXT_robustness.txt
        glGetGraphicsResetStatus = (glGetGraphicsResetStatus_func)resolveFunction("glGetGraphicsResetStatusEXT");
        glReadnPixels = (glReadnPixels_func)resolveFunction("glReadnPixelsEXT");
        glGetnUniformfv = (glGetnUniformfv_func)resolveFunction("glGetnUniformfvEXT");
    } else {
        glGetGraphicsResetStatus = KWin::GetGraphicsResetStatus;
        glReadnPixels = KWin::ReadnPixels;
        glGetnUniformfv = KWin::GetnUniformfv;
    }
}
 
static GLenum GetGraphicsResetStatus()
{
    return GL_NO_ERROR;
}
 
static void ReadnPixels(GLint x, GLint y, GLsizei width, GLsizei height, GLenum format,
                        GLenum type, GLsizei bufSize, GLvoid *data)
{
    glReadPixels(x, y, width, height, format, type, data);
}
 
static void GetnUniformfv(GLuint program, GLint location, GLsizei bufSize, GLfloat *params)
{
    glGetUniformfv(program, location, params);
}
 
} // namespace