#11371 Remove GLU dependency to fix Windows build error

GL/glu.h conflicts with Qt's OpenGL headers on Windows due to APIENTRY
redefinition. Replace gluBuild2DMipmaps with glTexImage2D + glGenerateMipmap,
and gluOrtho2D with glOrtho.

Author: kriben

Fwk/VizFwk/LibRender/cvfOpenGL.h

@@ -51,11 +51,12 @@
     QOpenGLExtraFunctions* cvfGL = QOpenGLContext::currentContext()->extraFunctions()
 
 // Include standard OpenGL headers for constants and basic types
+// Note: Qt's QOpenGLFunctions headers already include the platform GL headers,
+// but we include them explicitly for clarity. GLU is not used.
 #if defined(WIN32) || defined(CVF_LINUX)
 
 // Windows and Linux includes
 #include <GL/gl.h>
-#include <GL/glu.h>
 
 #elif defined(CVF_ANDROID)
 
@@ -73,7 +74,6 @@
 
 // Mac OSX includes
 #include "OpenGL/gl.h"
-#include "OpenGL/glu.h"
 
 #endif
 

Fwk/VizFwk/LibRender/cvfTexture2D_FF.cpp

@@ -146,9 +146,8 @@ bool Texture2D_FF::setupTexture(OpenGLContext* oglContext)
     GLsizei width = static_cast<GLsizei>(m_image->width());
     GLsizei height = static_cast<GLsizei>(m_image->height());
     CVF_ASSERT(height > 0 && width > 0);
-    //glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, m_image->ptr());
-    // Note: gluBuild2DMipmaps will scale the image to the closest power of 2 dimension, which is required by the software renderer
-    gluBuild2DMipmaps(GL_TEXTURE_2D, 4, width, height, GL_RGBA, GL_UNSIGNED_BYTE, m_image->ptr());
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, m_image->ptr());
+    cvfGL->glGenerateMipmap(GL_TEXTURE_2D);
 
     if (CVF_TEST_AND_REPORT_OPENGL_ERROR(oglContext, "Setup texture"))
     {

Fwk/VizFwk/TestApps/Win32/Win32SnippetRunner/Win32SnippetRunner.cpp

@@ -43,7 +43,6 @@
 #include "Win32PropertiesPanel.h"
 
 #include <GL/gl.h>
-#include <GL/glu.h>
 
 #include "SnippetFactoryBasis.h"
 

Fwk/VizFwk/Tests/SnippetsBasis/snipDepthPeelingFront.cpp

@@ -536,7 +536,7 @@ void DepthPeelingFront::drawQuad()
     glMatrixMode(GL_MODELVIEW);
     glPushMatrix();
     glLoadIdentity();
-    gluOrtho2D(0.0, 1.0, 0.0, 1.0);
+    glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
     glBegin(GL_QUADS);
     {
         glVertex2f(0.0, 0.0); 

Fwk/VizFwk/Tests/SnippetsBasis/snipIncrementalRenderer.cpp

@@ -213,7 +213,7 @@ void IncrementalRenderer::onPaintEvent(PostEventAction* postEventAction)
     //glViewport(0, 0, vpWidth, vpHeight);
     glMatrixMode(GL_PROJECTION);
     glLoadIdentity();
-    gluOrtho2D(0, vpWidth, 0, vpHeight);
+    glOrtho(0, vpWidth, 0, vpHeight, -1, 1);
 
     glMatrixMode(GL_MODELVIEW);
     glLoadIdentity();