我想进入Metal。我已经完成了一些OpenGL,但它已经好几年了,所以我无法想出这样做的正确方法。我一直在使用Ray Wenderlich的金属教程介绍(http://www.raywenderlich.com/81399/ios-8-metal-tutorial-swift-moving-to-3d)
我有一个Vertex结构:
struct Vertex
{
var x, y, z: Float
var r, g, b, a: Float
func floatBuffer() -> Array<Float>
{
return [x, y, z, r, g, b, a]
}
}
和顶点缓冲类:
class VertexBuffer
{
var vertexData = Array<Float>()
init(vertices: Array<Vertex>)
{
var vertexData = Array<Float>()
for vertex in vertices
{
vertexData += vertex.floatBuffer()
}
self.vertexData = vertexData
}
func updateColorOfVertexAtIndex(index: Int, newRed: CGFloat, newGreen: CGFloat, newBlue: CGFloat, newAlpha: CGFloat)
{
let vertexDataIndex = index * 7
if (vertexDataIndex < self.vertexData.count)
{
self.vertexData[vertexDataIndex + 3] = Float(newRed)
self.vertexData[vertexDataIndex + 4] = Float(newGreen)
self.vertexData[vertexDataIndex + 5] = Float(newBlue)
self.vertexData[vertexDataIndex + 6] = Float(newAlpha)
}
}
func updateColorOfVertexAtIndex(index: Int, newColor: UIColor)
{
var red: CGFloat = 0.0
var green: CGFloat = 0.0
var blue: CGFloat = 0.0
var alpha: CGFloat = 0.0
newColor.getRed(&red, green: &green, blue: &blue, alpha: &alpha)
self.updateColorOfVertexAtIndex(index, newRed: red, newGreen: green, newBlue: blue, newAlpha: alpha)
}
}
根据其他一些应用程序的状态,我想更新一个或多个顶点的RGBA。使用VertexBuffer.updateColor...
方法,我将更新VertexBuffer.vertexData
中的相应RGBA值。我有一个CADisplayLink连接到下面的函数:
func diffusionLoop()
{
self.updateVertexData()
var vertexData = self.inkVertexBuffer.vertexData
let dataSize = vertexData.count * sizeofValue(vertexData[0])
let vertexBuffer = self.device.newBufferWithBytes(vertexData, length: dataSize, options: nil)
autoreleasepool { () -> () in
self.renderColorsWithVertexBuffer(vertexBuffer)
}
}
func renderColorsWithVertexBuffer(vertexBuffer: MTLBuffer)
{
let renderPassDescriptor = MTLRenderPassDescriptor()
let drawable = self.metalLayer.nextDrawable()
renderPassDescriptor.colorAttachments[0].texture = drawable.texture
renderPassDescriptor.colorAttachments[0].loadAction = .Clear
renderPassDescriptor.colorAttachments[0].clearColor = MTLClearColorMake(1.0, 1.0, 1.0, 0.0)
renderPassDescriptor.colorAttachments[0].storeAction = .Store
let commandBuffer = self.commandQueue.commandBuffer()
if let renderEncoder = commandBuffer.renderCommandEncoderWithDescriptor(renderPassDescriptor) {
renderEncoder.setRenderPipelineState(self.pipelineState)
renderEncoder.setVertexBuffer(vertexBuffer, offset: 0, atIndex: 0)
renderEncoder.drawPrimitives(.Triangle, vertexStart: 0, vertexCount: self.vertexCount, instanceCount: self.triangleCount)
renderEncoder.endEncoding()
}
commandBuffer.presentDrawable(drawable)
commandBuffer.commit()
}
问题是,我不知道这是否是正确的方法。我的目的是经常更新某些顶点的颜色,但是每次修改顶点数据并创建一个MTLBuffer的答案是什么?或其他什么?
任何帮助将不胜感激!
答案 0 :(得分:2)
理想情况下,您不希望更新 vertexBuffer 的值。在我看来,你要做的最好的方法是将不可变数据与可变数据分开。
所以我会用颜色值创建单独的统一缓冲区并更新它而不是 vertexBuffer 本身。
你还说“ 基于我想要更新一个或多个顶点的RGBA的其他一些应用程序的状态...... ”,它可能会更好将那些“状态”作为常量传递给着色器和着色器内部,以计算每个顶点或片段的颜色。
顶点着色器有:
unsigned int vid [[ vertex_id ]]
您可以使用它明确设置每个顶点的颜色。