Added texture checks

* Quadratic shape
* Dimensions a power of 2
* Maximum size (automatic scaling if exceeded)
* Also: removed simple background

src/pulsaranimationwidget.cpp

@@ -164,10 +164,49 @@ void PulsarAnimationWidget::initializeGL()
     gluQuadricNormals(m_quadricPulsarSpinAxis, GLU_SMOOTH);
     gluQuadricNormals(m_quadricPulsarMagneticAxis, GLU_SMOOTH);
 
-    // load textures
-    m_pulsarTexture = bindTexture(QImage(":/textures/resources/texture_pulsar.png"), GL_TEXTURE_2D, GL_RGBA);
-//    m_backgroundTexture = bindTexture(QImage(":/textures/resources/texture_background_simple.png"), GL_TEXTURE_2D, GL_RGBA);
-    m_backgroundTexture = bindTexture(QImage(":/textures/resources/texture_background_carina.jpg"), GL_TEXTURE_2D, GL_RGB);
+    // query max texture size (estimate)
+    GLint maxTextureSize;
+    glGetIntegerv(GL_MAX_TEXTURE_SIZE, &maxTextureSize);
+
+    // prepare and check pulsar texture
+    QImage pulsarTexture(":/textures/resources/texture_pulsar.png");
+    if(pulsarTexture.width() != pulsarTexture.height()) {
+    	qWarning("Warning: pulsar texture shape not quadratic!");
+    }
+    else {
+    	double integer = 0.0;
+    	double fraction = 0.0;
+    	fraction = modf(log(pulsarTexture.width()) / log(2.0), &integer);
+    	if(fraction > 0.0) {
+    		qWarning("Warning: pulsar texture dimensions not a power of 2!");
+    	}
+    }
+    if(pulsarTexture.width() > maxTextureSize) {
+    	qDebug("Warning: maximum texture size exceeded! Scaling down pulsar texture to %ix%i...", maxTextureSize, maxTextureSize);
+    	pulsarTexture = pulsarTexture.scaled(maxTextureSize, maxTextureSize, Qt::IgnoreAspectRatio, Qt::SmoothTransformation);
+    }
+
+    // prepare and check background texture
+    QImage backgroundTexture(":/textures/resources/texture_background_carina.jpg");
+    if(backgroundTexture.width() != backgroundTexture.height()) {
+    	qWarning("Warning: invalid background texture shape!");
+    }
+    else {
+    	double integer = 0.0;
+    	double fraction = 0.0;
+    	fraction = modf(log(backgroundTexture.width()) / log(2.0), &integer);
+    	if(fraction > 0.0) {
+    		qWarning("Warning: background texture dimensions not a power of 2!");
+    	}
+    }
+    if(backgroundTexture.width() > maxTextureSize) {
+    	qDebug("Warning: maximum texture size exceeded! Scaling down background texture to %ix%i...", maxTextureSize, maxTextureSize);
+    	backgroundTexture = backgroundTexture.scaled(maxTextureSize, maxTextureSize, Qt::IgnoreAspectRatio, Qt::SmoothTransformation);
+    }
+
+    // bind textures
+    m_pulsarTexture = bindTexture(pulsarTexture, GL_TEXTURE_2D, GL_RGBA);
+    m_backgroundTexture = bindTexture(backgroundTexture, GL_TEXTURE_2D, GL_RGB);
 
     // use mipmapped textures
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);