Precompute values & reserve memory in CreateFrameRects()

Reduce the number of calculations in nested loops, and reserve the needed amount of memory instead of relying on the vector to resize itself.

src/RageTexture.cpp

@@ -28,15 +28,22 @@ void RageTexture::CreateFrameRects()
 
 	// Fill in the m_FrameRects with the bounds of each frame in the animation.
 	m_TextureCoordRects.clear();
+	m_TextureCoordRects.reserve(static_cast<size_t>(m_iFramesWide * m_iFramesHigh));
+
+	float frameWidth = (m_iImageWidth / static_cast<float>(m_iTextureWidth)) / m_iFramesWide;
+	float frameHeight = (m_iImageHeight / static_cast<float>(m_iTextureHeight)) / m_iFramesHigh;
 
 	for( int j=0; j<m_iFramesHigh; j++ )		// traverse along Y
 	{
+		float top = j * frameHeight;
+		float bottom = (j + 1) * frameHeight;
+
 		for( int i=0; i<m_iFramesWide; i++ )	// traverse along X (important that this is the inner loop)
 		{
-			RectF frect( (i+0)/(float)m_iFramesWide*m_iImageWidth /(float)m_iTextureWidth,	// these will all be between 0.0 and 1.0
-						 (j+0)/(float)m_iFramesHigh*m_iImageHeight/(float)m_iTextureHeight,
-						 (i+1)/(float)m_iFramesWide*m_iImageWidth /(float)m_iTextureWidth,
-						 (j+1)/(float)m_iFramesHigh*m_iImageHeight/(float)m_iTextureHeight );
+			float left = i * frameWidth;
+			float right = (i + 1) * frameWidth;
+
+			RectF frect(left, top, right, bottom);  // these will all be in the range [0.0,1.0]
 			m_TextureCoordRects.push_back( frect );	// the index of this array element will be (i + j*m_iFramesWide)
 
 			//LOG->Trace( "Adding frect%d %f %f %f %f", (i + j*m_iFramesWide), frect.left, frect.top, frect.right, frect.bottom );