C++ StelProjectorP::getDefaultAngleForGravityText方法代码示例

//.........这里部分代码省略.........
		// Both X and Y need to be at least 1 so we don't create an empty image 
		// (doesn't work with textures)
		const int requiredWidth  = std::max(1, extents.width() + 1 + static_cast<int>(0.02f * extents.width()));
		const int requiredHeight = std::max(1, extents.height());
		// Create temporary image and render text into it

		// QImage is used solely to reuse existing QGLTextureBackend constructor 
		// function. QPixmap could be used as well (not sure which is faster, 
		// needs profiling)
		QImage image = areNonPowerOfTwoTexturesSupported() 
		             ? QImage(requiredWidth, requiredHeight, QImage::Format_ARGB32_Premultiplied) 
		             : QImage(StelUtils::smallestPowerOfTwoGreaterOrEqualTo(requiredWidth), 
		                      StelUtils::smallestPowerOfTwoGreaterOrEqualTo(requiredHeight),
		                      QImage::Format_ARGB32);
		image.fill(Qt::transparent);

		QPainter fontPainter(&image);
		fontPainter.setFont(painter->font());
		fontPainter.setRenderHints(QPainter::TextAntialiasing, true);
		fontPainter.setPen(Qt::white);

		// The second argument ensures the text is positioned correctly even if 
		// the image is enlarged to power-of-two.
		fontPainter.drawText(-extents.x(), 
		                     image.height() - requiredHeight - extents.y(), 
		                     params.string_);

		textTexture = StelQGLTextureBackend::constructFromImage
			(this, QString(), TextureParams().filtering(TextureFiltering_Linear), image);
		const QSize size = textTexture->getDimensions();
		if(!textTexture->getStatus() == TextureStatus_Loaded)
		{
			qWarning() << "Texture error: " << textTexture->getErrorMessage();
			Q_ASSERT_X(false, Q_FUNC_INFO, "Failed to construct a text texture");
		}
		textTextureCache.insert(hash, textTexture, 4 * size.width() * size.height());
	}

	// Even if NPOT textures are not supported, we always draw the full rectangle 
	// of the texture. The extra space is fully transparent, so it's not an issue.

	// Shortcut variables to calculate the rectangle.
	const QSize size   = textTexture->getDimensions();
	const float w      = size.width();
	const float h      = size.height();
	const float xShift = params.xShift_;
	const float yShift = params.yShift_;

	const float angleDegrees = 
		params.angleDegrees_ + 
		(params.noGravity_ ? 0.0f : projector->getDefaultAngleForGravityText());
	// Zero out very small angles.
	// 
	// (this could also be used to optimize the case with zero angled
	//  to avoid sin/cos if needed)
	const bool  angled = std::fabs(angleDegrees) >= 1.0f * M_PI / 180.f;
	const float cosr   = angled  ? std::cos(angleDegrees * M_PI / 180.0) : 1.0f;
	const float sinr   = angled  ? std::sin(angleDegrees * M_PI / 180.0) : 0.0f;

	// Corners of the (possibly rotated) texture rectangle.
	const Vec2f ne(round(x + cosr * xShift       - sinr * yShift),
	               round(y + sinr * xShift       + cosr * yShift));
	const Vec2f nw(round(x + cosr * (w + xShift) - sinr * yShift),
	               round(y + sinr * (w + xShift) + cosr * yShift));
	const Vec2f se(round(x + cosr * xShift       - sinr * (h + yShift)),
	               round(y + sinr * xShift       + cosr * (h + yShift)));
	const Vec2f sw(round(x + cosr * (w + xShift) - sinr * (h + yShift)),
	               round(y + sinr * (w + xShift) + cosr * (h + yShift)));

	// Construct the text vertex buffer if it doesn't exist yet, otherwise clear it.
	if(NULL == textBuffer)
	{
		textBuffer = createVertexBuffer<TexturedVertex>(PrimitiveType_TriangleStrip);
	}
	else
	{
		textBuffer->unlock();
		textBuffer->clear();
	}

	textBuffer->addVertex(TexturedVertex(ne, Vec2f(0.0f, 0.0f)));
	textBuffer->addVertex(TexturedVertex(nw, Vec2f(1.0f, 0.0f)));
	textBuffer->addVertex(TexturedVertex(se, Vec2f(0.0f, 1.0f)));
	textBuffer->addVertex(TexturedVertex(sw, Vec2f(1.0f, 1.0f)));
	textBuffer->lock();

	// Draw.
	const BlendMode oldBlendMode = blendMode;
	setBlendMode(BlendMode_Alpha);
	textTexture->bind(0);
	drawVertexBuffer(textBuffer);
	setBlendMode(oldBlendMode);

	// Reset user-bound texture.
	if(NULL != currentTexture)
	{
		currentTexture->bind(0);
	}
	viewport.disablePainting();
}