metal

I am trying to implement a metal-backed drawing application where brushstrokes are drawn on an MTKView by textured square repeatedly along a finger position. I am drawing this with alpha 0.2. When the squares are overlapped the color is added. How can I draw with alpha 0.2. I think you need to draw the brush squares to a separate texture, initially cleared to transparent, without blending. Then draw that whole texture to your view with blending. If you draw the brush squares directly to the view, then they will accumulate. After you draw square 1, it's part of the image. Metal can no longer

I'm creating a MTLTexture from CVImageBuffer s (from camera and players) using CVMetalTextureCacheCreateTextureFromImage to get a CVMetalTexture and then CVMetalTextureGetTexture to get the MTLTexture . The problem I'm seeing is that when I later render the texture using Metal, I occasionally see video frames rendered out of order (visually it stutters back and forth in time), presumably because CoreVideo is modifying the underlying CVImageBuffer storage and the MTLTexture is just pointing there. Is there any way to make CoreVideo not touch that buffer and use another one from its pool until I

I'm looking for just a working Metal shader that works in SceneKit with SCNProgram. Can someone show me the correct method declarations/how to hook this up? let program = SCNProgram() program.vertexFunctionName = "myVertex" program.fragmentFunctionName = "myFragment" material.program = program and then the shader //MyShader.metal vertex something myVertex(something) { return something; } fragment float4 myFragment(something) { return something } I'm just looking for the most basic example please. I clipped out all the 'unnecessary' stuff, this is about as basic as it gets and pretty much what

While using Apple's texture importer , or my own, a white soft-edged circle drawn in software (with a transparent bg) or in Photoshop (saved as a PNG) when rendered will have its semi-transparent colors replaced with black when brought into Metal. Below is a screen grab from Xcode's Metal debugger, you can see the texture before being sent to shaders. Image located here (I'm not high ranked enough to embed) In Xcode, finder, and when put into an UIImageView, the source texture does not have the ring. But somewhere along the UIImage -> CGContex -> MTLTexture process (I'm thinking specifically

I tried: let scale = UIScreen.mainScreen().scale UIGraphicsBeginImageContextWithOptions(metalLayer.bounds.size,false,scale) // metalLayer.renderInContext(UIGraphicsGetCurrentContext()!) // self.view.layer ... metalLayer.presentationLayer()!.renderInContext(UIGraphicsGetCurrentContext()!) let image = UIGraphicsGetImageFromCurrentImageContext() UIGraphicsEndImageContext(); UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil) But the result is a empty screenshot. Any help would be nice! Please keep in mind that i want to take a snapshot of a CAMetalLayer To make a screenshot, you need to get