Only draw framebuffer is frame is not overdue

include/window.hpp

@@ -84,6 +84,7 @@ struct Window {
 	/** The last known absolute mouse position in the window */
 	math::Vec mousePos;
 	std::shared_ptr<Font> uiFont;
+	double frameTimeStart = 0.f;
 
 	struct Internal;
 	Internal *internal;
@@ -100,6 +101,7 @@ struct Window {
 	int getMods();
 	void setFullScreen(bool fullScreen);
 	bool isFullScreen();
+	bool isFrameOverdue();
 
 	std::shared_ptr<Font> loadFont(const std::string &filename);
 	std::shared_ptr<Image> loadImage(const std::string &filename);

src/app/RackScrollWidget.cpp

@@ -18,11 +18,7 @@ RackScrollWidget::RackScrollWidget() {
 }
 
 void RackScrollWidget::step() {
-	// Set ZoomWidget's zoom every few frames
-	int frame = APP->window->frame;
-	if (frame % 10 == 0) {
-		zoom->setZoom(std::round(settings.zoom * 100) / 100);
-	}
+	zoom->setZoom(std::round(settings.zoom * 100) / 100);
 
 	// Resize RackWidget to be a bit larger than the viewport
 	rack->box.size = box.size

src/widget/FramebufferWidget.cpp

@@ -18,87 +18,92 @@ FramebufferWidget::~FramebufferWidget() {
 void FramebufferWidget::step() {
 	Widget::step();
 
-	// if (random::uniform() > 0.01)
-	// 	return;
-
-	// Render to framebuffer if dirty.
-	// Also check that scale has been set by `draw()` yet.
-	if (dirty && !scale.isZero()) {
-		// In case we fail drawing the framebuffer, don't try again the next frame, so reset `dirty` here.
-		dirty = false;
-		NVGcontext *vg = APP->window->vg;
-
-		fbScale = scale;
-		// Get subpixel offset in range [0, 1)
-		math::Vec offsetI = offset.floor();
-		fbOffset = offset.minus(offsetI);
-
-		math::Rect localBox;
-		if (children.empty()) {
-			localBox = box.zeroPos();
-		}
-		else {
-			localBox = getChildrenBoundingBox();
-		}
-
-		// DEBUG("%g %g %g %g, %g %g, %g %g", RECT_ARGS(localBox), VEC_ARGS(fbOffset), VEC_ARGS(fbScale));
-		// Transform to world coordinates, then expand to nearest integer coordinates
-		math::Vec min = localBox.getTopLeft().mult(fbScale).plus(fbOffset).floor();
-		math::Vec max = localBox.getBottomRight().mult(fbScale).plus(fbOffset).ceil();
-		fbBox = math::Rect::fromMinMax(min, max);
-		// DEBUG("%g %g %g %g", RECT_ARGS(fbBox));
-
-		math::Vec newFbSize = fbBox.size.mult(APP->window->pixelRatio).ceil();
-
-		// Create framebuffer if a new size is needed
-		if (!fb || !newFbSize.isEqual(fbSize)) {
-			fbSize = newFbSize;
-			// Delete old framebuffer
-			if (fb)
-				nvgluDeleteFramebuffer(fb);
-			// Create a framebuffer at the oversampled size
-			if (fbSize.isFinite() && !fbSize.isZero())
-				fb = nvgluCreateFramebuffer(vg, fbSize.x * oversample, fbSize.y * oversample, 0);
-		}
-
-		if (!fb)
-			return;
+	// It's more important to not lag the frame than to draw the framebuffer
+	if (APP->window->isFrameOverdue())
+		return;
 
-		nvgluBindFramebuffer(fb);
-		drawFramebuffer();
-		nvgluBindFramebuffer(NULL);
+	// Check that scale has been set by `draw()` yet.
+	if (scale.isZero())
+		return;
 
-		// If oversampling, create another framebuffer and copy it to actual size.
-		if (oversample != 1.0) {
-			NVGLUframebuffer *newFb = nvgluCreateFramebuffer(vg, fbSize.x, fbSize.y, 0);
-			if (!newFb)
-				return;
+	// Only redraw if FramebufferWidget is dirty
+	if (!dirty)
+		return;
 
-			// Use NanoVG for resizing framebuffers
-			nvgluBindFramebuffer(newFb);
+	// In case we fail drawing the framebuffer, don't try again the next frame, so reset `dirty` here.
+	dirty = false;
+	NVGcontext *vg = APP->window->vg;
 
-			nvgBeginFrame(vg, fbBox.size.x, fbBox.size.y, 1.0);
+	fbScale = scale;
+	// Get subpixel offset in range [0, 1)
+	math::Vec offsetI = offset.floor();
+	fbOffset = offset.minus(offsetI);
 
-			// Draw oversampled framebuffer
-			nvgBeginPath(vg);
-			nvgRect(vg, 0.0, 0.0, fbSize.x, fbSize.y);
-			NVGpaint paint = nvgImagePattern(vg, 0.0, 0.0, fbSize.x, fbSize.y,
-				0.0, fb->image, 1.0);
-			nvgFillPaint(vg, paint);
-			nvgFill(vg);
+	math::Rect localBox;
+	if (children.empty()) {
+		localBox = box.zeroPos();
+	}
+	else {
+		localBox = getChildrenBoundingBox();
+	}
 
-			glViewport(0.0, 0.0, fbSize.x, fbSize.y);
-			glClearColor(0.0, 0.0, 0.0, 0.0);
-			glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
-			nvgEndFrame(vg);
-			nvgReset(vg);
+	// DEBUG("%g %g %g %g, %g %g, %g %g", RECT_ARGS(localBox), VEC_ARGS(fbOffset), VEC_ARGS(fbScale));
+	// Transform to world coordinates, then expand to nearest integer coordinates
+	math::Vec min = localBox.getTopLeft().mult(fbScale).plus(fbOffset).floor();
+	math::Vec max = localBox.getBottomRight().mult(fbScale).plus(fbOffset).ceil();
+	fbBox = math::Rect::fromMinMax(min, max);
+	// DEBUG("%g %g %g %g", RECT_ARGS(fbBox));
 
-			nvgluBindFramebuffer(NULL);
+	math::Vec newFbSize = fbBox.size.mult(APP->window->pixelRatio).ceil();
 
-			// Swap the framebuffers
+	// Create framebuffer if a new size is needed
+	if (!fb || !newFbSize.isEqual(fbSize)) {
+		fbSize = newFbSize;
+		// Delete old framebuffer
+		if (fb)
 			nvgluDeleteFramebuffer(fb);
-			fb = newFb;
-		}
+		// Create a framebuffer at the oversampled size
+		if (fbSize.isFinite() && !fbSize.isZero())
+			fb = nvgluCreateFramebuffer(vg, fbSize.x * oversample, fbSize.y * oversample, 0);
+	}
+
+	if (!fb)
+		return;
+
+	nvgluBindFramebuffer(fb);
+	drawFramebuffer();
+	nvgluBindFramebuffer(NULL);
+
+	// If oversampling, create another framebuffer and copy it to actual size.
+	if (oversample != 1.0) {
+		NVGLUframebuffer *newFb = nvgluCreateFramebuffer(vg, fbSize.x, fbSize.y, 0);
+		if (!newFb)
+			return;
+
+		// Use NanoVG for resizing framebuffers
+		nvgluBindFramebuffer(newFb);
+
+		nvgBeginFrame(vg, fbBox.size.x, fbBox.size.y, 1.0);
+
+		// Draw oversampled framebuffer
+		nvgBeginPath(vg);
+		nvgRect(vg, 0.0, 0.0, fbSize.x, fbSize.y);
+		NVGpaint paint = nvgImagePattern(vg, 0.0, 0.0, fbSize.x, fbSize.y,
+			0.0, fb->image, 1.0);
+		nvgFillPaint(vg, paint);
+		nvgFill(vg);
+
+		glViewport(0.0, 0.0, fbSize.x, fbSize.y);
+		glClearColor(0.0, 0.0, 0.0, 0.0);
+		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
+		nvgEndFrame(vg);
+		nvgReset(vg);
+
+		nvgluBindFramebuffer(NULL);
+
+		// Swap the framebuffers
+		nvgluDeleteFramebuffer(fb);
+		fb = newFb;
 	}
 }
 

src/window.cpp

@@ -308,7 +308,7 @@ void Window::run() {
 
 	frame = 0;
 	while(!glfwWindowShouldClose(win)) {
-		double startTime = glfwGetTime();
+		frameTimeStart = glfwGetTime();
 
 		// Poll events
 		glfwPollEvents();
@@ -382,9 +382,9 @@ void Window::run() {
 		}
 
 		// Limit frame rate
-		double endTime = glfwGetTime();
+		double frameTimeEnd = glfwGetTime();
 		if (settings.frameRateLimit > 0.0) {
-			double frameDuration = endTime - startTime;
+			double frameDuration = frameTimeEnd - frameTimeStart;
 			double waitDuration = 1.0 / settings.frameRateLimit - frameDuration;
 			if (waitDuration > 0.0) {
 				std::this_thread::sleep_for(std::chrono::duration<double>(waitDuration));
@@ -392,7 +392,7 @@ void Window::run() {
 		}
 
 		// Compute actual frame rate
-		endTime = glfwGetTime();
+		frameTimeEnd = glfwGetTime();
 		// DEBUG("%g fps", 1 / (endTime - startTime));
 		frame++;
 	}
@@ -449,6 +449,13 @@ bool Window::isFullScreen() {
 	return monitor != NULL;
 }
 
+bool Window::isFrameOverdue() {
+	if (settings.frameRateLimit == 0.0)
+		return false;
+	double frameDuration = glfwGetTime() - frameTimeStart;
+	return frameDuration > 1.0 / settings.frameRateLimit;
+}
+
 std::shared_ptr<Font> Window::loadFont(const std::string &filename) {
 	auto sp = internal->fontCache[filename].lock();
 	if (!sp)