在iOS金属中重用不同统一参数的像素着色器

时间:2015-05-05 22:57:31

标签: ios metal

我在使用不同均匀参数的不同对象重复使用金属像素和顶点着色器时遇到问题。我猜它与我错误地使用命令缓冲区有关。

当我运行我的金属应用程序时,几何体正确绘制,但只有最后调用的制服

renderCommand setFragmentBuffer:uniform_info offset:0 atIndex:UNIFORM_INFO_BUFFER_INDEX];

似乎将数据写入像素着色器。

我在这里剪切(和编辑)了我的渲染循环。我正在寻找一个示例,说明如何在单个渲染过程中多次重复使用我的像素着色器,并传入不同的制服。

  CAMetalLayer *metalLayer = [metal_info.g_iosMetalView getMetalLayer];

  id <CAMetalDrawable> frameDrawable;
  while (!frameDrawable){
     frameDrawable = [metalLayer nextDrawable];
  }
  MTLRenderPassDescriptor *mtlRenderPassDescriptor;
  mtlRenderPassDescriptor = [MTLRenderPassDescriptor new];
  mtlRenderPassDescriptor.colorAttachments[0].texture = frameDrawable.texture;
  mtlRenderPassDescriptor.colorAttachments[0].loadAction = MTLLoadActionLoad;
  mtlRenderPassDescriptor.colorAttachments[0].clearColor = MTLClearColorMake(0.0, 0.0, 1.0, 1.0);

  mtlRenderPassDescriptor.depthAttachment.texture = metal_info.g_depthTexture;
  mtlRenderPassDescriptor.depthAttachment.loadAction = MTLLoadActionClear;
  mtlRenderPassDescriptor.depthAttachment.storeAction = MTLStoreActionStore;
  mtlRenderPassDescriptor.depthAttachment.clearDepth = 1.0;

  // Create My one and only command buffer
  id <MTLCommandBuffer> mtlCommandBuffer = [metal_info.g_commandQueue commandBuffer];

  int n = RendererInfo.fact.GetActiveCount();

  // loop through all the objects I have (I'm having trouble with 2)
  Object* curObj = NULL;
  for (int obj_i = 0 ; obj_i < n ; ++obj_i)
  {
     // create one render encoder for each object
     id <MTLRenderCommandEncoder> renderCommand = [mtlCommandBuffer renderCommandEncoderWithDescriptor: mtlRenderPassDescriptor];

     memcpy([metal_info.g_projectionMatrix contents], &metal_info.g_Projection, sizeof(Matrix4f));         
     Matrix4f *view = RendererInfo.cam->GetViewMatrix();
     memcpy([metal_info.g_viewMatrix contents], view, sizeof(Matrix4f));

     [renderCommand setFrontFacingWinding:MTLWindingCounterClockwise];
     [renderCommand setCullMode:MTLCullModeBack]; 

     [renderCommand setViewport: (MTLViewport){ 0.0, 0.0,
        (double)metal_info.g_metal_width,
        (double)metal_info.g_metal_height,
        0.0, 1.0 }];

     [renderCommand setRenderPipelineState:metal_info.g_pipelineState];
     [renderCommand setDepthStencilState:metal_info.g_depthState];


     curObj = RendererInfo.fact.GetObjectAtIndex(obj_i);

     id<MTLBuffer> vertices = curObj->GetVertexBuffer();
     id<MTLBuffer> indicies = curObj->GetIndexBuffer();         
     int indexCount = curObj->GetIndexCount();

     id <MTLTexture> texture = objTexture->GetAsset();
     [renderCommand setFragmentTexture:texture atIndex:0];         

     memcpy([metal_info.g_shaderUniformInfo contents], curObj->GetUniformInfo(), curObj->curObj->GetUniformInfoSize());

     [renderCommand setVertexBuffer:vertices                       offset:0 atIndex:VERTICES__INDEX];
     [renderCommand setVertexBuffer:metal_info.g_viewMatrix        offset:0 atIndex:VIEW_MATRIX_BUFFER_INDEX];
     [renderCommand setVertexBuffer:metal_info.g_projectionMatrix  offset:0 atIndex:PROJECTION_MATRIX_BUFFER_INDEX];

     [renderCommand setFragmentBuffer:metal_info.g_shaderUniformInfo  offset:0 atIndex:UNIFORM_INFO_BUFFER_INDEX];

     [renderCommand drawIndexedPrimitives:MTLPrimitiveTypeTriangle
                               indexCount:indexCount
                               indexType:MTLIndexTypeUInt32
                             indexBuffer:indicies
                       indexBufferOffset:0];

     [renderCommand endEncoding];
  }
  [mtlCommandBuffer presentDrawable:frameDrawable];
  [mtlCommandBuffer commit];

如果需要,我也可以发布像素着色器,但是当我编码为一次只渲染一个对象时,着色器可以正常工作。

2 个答案:

答案 0 :(得分:2)

MTLRenderCommandEncoder不编码“memcpy”指令。您目前认为每个memcpy([metal_info.g_shaderUniformInfo contents], curObj->GetUniformInfo(), curObj->curObj->GetUniformInfoSize());都与编码器相关联,但实际上,您只是将相同的metal_info.g_shaderUniformInfo与每个编码器相关联,并且着色器都在使用该缓冲区中的数据缓冲区已提交 - 编码器不捕获缓冲区的副本。你注意到的关键是,这个提交是在你最后一次循环之后发生的,此时g_shaderUniformInfo具有唯一有意义使用的值。

您需要为每个对象使用不同的统一缓冲区,或者写入同一缓冲区的不同部分,并从中适当地读取它们。

答案 1 :(得分:0)

正如@Jessy所说,Metal并没有复制你的数据,因此只会有效地使用上次迭代的数据。

我想补充一点,如果您的缓冲区很小(<4KB左右),您可以使用setVertexBytessetFragmentBytes替代 复制字节,而不必处理创建MTLBuffer等等。这是一个很好的便利方法。