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I have created a 3D model of a local outdoor performance space and I have an app that usesMetal on MacOS 10.14.2 to display the model. I want to create an animationby flying the camera around the scene, while record each frame. I know how to dothe animated fly-around and I know how to create a video frame-by-frame withAVFoundation. The step for which I can find no information is how I can capture each frame.I have a completion handler so I know when the gpu has finished each command buffer.But what is the best way to get the image in space?I thought perhaps I could do this by attaching a second texture to colorAttachments[1]but this has resulted in some odd behavior where the original scene that used to fill myMTKView window now occupies just the upper left quadrant of the window.What I was trying to do is write the same color to both colorAttachments[0] (my screen) and tocolorAttachments[1]. In my shader I defined:struct FragmentOut { float4 color0 [[ color(0) ]]; float4 color1 [[ color(1) ]];};My fragment shader looks like:fragment FragmentOut grove_fragment_function(VertexOut vIn [[ stage_in ]], constant Uniforms &uniforms [[buffer(1)]]) {....float4 color = diffuseColor + ambientColor + specularColor; out.color0 = color; out.color1 = color; return out;}My hope was that I could then use something like:offScreenTextureBuffer?.getBytes(buffer, bytesPerRow: 4 * w, from: MTLRegionMake2D(0, 0, w, h), mipmapLevel: 0)to transfer the image data to a local buffer.This doesn't seem to work, plus I have the unexpected display behavior noted above.I am configuring the offScreenTextureBuffer thus:let pixelFormat = MTLPixelFormat.bgra8Unorm_srgbvar offScreenBufferDescriptor = MTLTextureDescriptor.texture2DDescriptor(pixelFormat: pixelFormat, width: 1000, height: 600, mipmapped: false)offScreenBufferDescriptor.usage = [.renderTarget, .shaderRead]offScreenTextureBuffer = device.makeTexture(descriptor: offScreenBufferDescriptor)

I have an NSTableView which shows the longitude and latitude points of objects on a map. Some objects, like trails, have many rows in the table. When I change objects I want to update the NSTableView and then select row 0. I tried [obectCoordTable reloadData]; [objectCoordTable selectRowIndexes: [NSIndexSet indexSetWithIndex: 0] byExtendingSelection: NO];This does not work because reloadData does not reload the table. It only schedules a reload for some time later(on next iteration of Main Loop?). So my attempt to select row 0 happens first. Then just before the tabledata are reloaded a (void)tableViewSelectionDidChange: happens with selected row reset to -1. So myselection of row 0 is ineffective.How do I select row 0 after the reload is finished? There seems to be no delegate method to notify the userwhen a complete data reload is completed.Do I have to schedule the selectRowIndexes for execution at a later time and hope it is after the data reload? That might work but seems a bit too hokey?Thanks.Richard Stover

I would like to draw text along a complex bezier curve. I've seen several examples on the web using CGPathApplyto do this. But those examples seem to be wrong. CGPathApply does not supply you with a series of points alongthe curve. I just get back the points, and control points, I just used to specify the Bezier curve. I want actualpixel coordinates of points along the curve. Is there some way to do this? Do I have to write my ownfunction to reproduce the Bezier curve points given the end points and control points? Has Apple documentedexactly the algorithm they use for doing this? Or is there some CG function I have overlooked thatdoes the evaluation for me? Or is there a CG function that takes a string and a path as arguments anddoes the job for me?Thanks.