// dear imgui: Renderer for Metal // This needs to be used along with a Platform Binding (e.g. OSX) // Implemented features: // [X] Renderer: User texture binding. Use 'MTLTexture' as ImTextureID. Read the FAQ about ImTextureID in imgui.cpp. // Missing features: // [ ] Renderer: Multi-viewport / platform windows. // You can copy and use unmodified imgui_impl_* files in your project. See main.cpp for an example of using this. // If you are new to dear imgui, read examples/README.txt and read the documentation at the top of imgui.cpp. // https://github.com/ocornut/imgui // CHANGELOG // (minor and older changes stripped away, please see git history for details) // 2018-11-30: Misc: Setting up io.BackendRendererName so it can be displayed in the About Window. // 2018-07-05: Metal: Added new Metal backend implementation. #include "imgui.h" #include "imgui_impl_metal.h" #import <Metal/Metal.h> // #import <QuartzCore/CAMetalLayer.h> // Not suported in XCode 9.2. Maybe a macro to detect the SDK version can be used (something like #if MACOS_SDK >= 10.13 ...) #import <simd/simd.h> #pragma mark - Support classes // A wrapper around a MTLBuffer object that knows the last time it was reused @interface MetalBuffer : NSObject @property (nonatomic, strong) id<MTLBuffer> buffer; @property (nonatomic, assign) NSTimeInterval lastReuseTime; - (instancetype)initWithBuffer:(id<MTLBuffer>)buffer; @end // An object that encapsulates the data necessary to uniquely identify a // render pipeline state. These are used as cache keys. @interface FramebufferDescriptor : NSObject<NSCopying> @property (nonatomic, assign) unsigned long sampleCount; @property (nonatomic, assign) MTLPixelFormat colorPixelFormat; @property (nonatomic, assign) MTLPixelFormat depthPixelFormat; @property (nonatomic, assign) MTLPixelFormat stencilPixelFormat; - (instancetype)initWithRenderPassDescriptor:(MTLRenderPassDescriptor *)renderPassDescriptor; @end // A singleton that stores long-lived objects that are needed by the Metal // renderer backend. Stores the render pipeline state cache and the default // font texture, and manages the reusable buffer cache. @interface MetalContext : NSObject @property (nonatomic, strong) id<MTLDepthStencilState> depthStencilState; @property (nonatomic, strong) FramebufferDescriptor *framebufferDescriptor; // framebuffer descriptor for current frame; transient @property (nonatomic, strong) NSMutableDictionary *renderPipelineStateCache; // pipeline cache; keyed on framebuffer descriptors @property (nonatomic, strong, nullable) id<MTLTexture> fontTexture; @property (nonatomic, strong) NSMutableArray<MetalBuffer *> *bufferCache; @property (nonatomic, assign) NSTimeInterval lastBufferCachePurge; - (void)makeDeviceObjectsWithDevice:(id<MTLDevice>)device; - (void)makeFontTextureWithDevice:(id<MTLDevice>)device; - (MetalBuffer *)dequeueReusableBufferOfLength:(NSUInteger)length device:(id<MTLDevice>)device; - (void)enqueueReusableBuffer:(MetalBuffer *)buffer; - (id<MTLRenderPipelineState>)renderPipelineStateForFrameAndDevice:(id<MTLDevice>)device; - (void)emptyRenderPipelineStateCache; - (void)renderDrawData:(ImDrawData *)drawData commandBuffer:(id<MTLCommandBuffer>)commandBuffer commandEncoder:(id<MTLRenderCommandEncoder>)commandEncoder; @end static MetalContext *g_sharedMetalContext = nil; #pragma mark - ImGui API implementation bool ImGui_ImplMetal_Init(id<MTLDevice> device) { ImGuiIO& io = ImGui::GetIO(); io.BackendRendererName = "imgui_impl_metal"; static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ g_sharedMetalContext = [[MetalContext alloc] init]; }); ImGui_ImplMetal_CreateDeviceObjects(device); return true; } void ImGui_ImplMetal_Shutdown() { ImGui_ImplMetal_DestroyDeviceObjects(); } void ImGui_ImplMetal_NewFrame(MTLRenderPassDescriptor *renderPassDescriptor) { IM_ASSERT(g_sharedMetalContext != nil && "No Metal context. Did you call ImGui_ImplMetal_Init?"); g_sharedMetalContext.framebufferDescriptor = [[FramebufferDescriptor alloc] initWithRenderPassDescriptor:renderPassDescriptor]; } // Metal Render function. void ImGui_ImplMetal_RenderDrawData(ImDrawData* draw_data, id<MTLCommandBuffer> commandBuffer, id<MTLRenderCommandEncoder> commandEncoder) { [g_sharedMetalContext renderDrawData:draw_data commandBuffer:commandBuffer commandEncoder:commandEncoder]; } bool ImGui_ImplMetal_CreateFontsTexture(id<MTLDevice> device) { [g_sharedMetalContext makeFontTextureWithDevice:device]; ImGuiIO& io = ImGui::GetIO(); io.Fonts->TexID = (__bridge void *)g_sharedMetalContext.fontTexture; // ImTextureID == void* return (g_sharedMetalContext.fontTexture != nil); } void ImGui_ImplMetal_DestroyFontsTexture() { ImGuiIO& io = ImGui::GetIO(); g_sharedMetalContext.fontTexture = nil; io.Fonts->TexID = nullptr; } bool ImGui_ImplMetal_CreateDeviceObjects(id<MTLDevice> device) { [g_sharedMetalContext makeDeviceObjectsWithDevice:device]; ImGui_ImplMetal_CreateFontsTexture(device); return true; } void ImGui_ImplMetal_DestroyDeviceObjects() { ImGui_ImplMetal_DestroyFontsTexture(); [g_sharedMetalContext emptyRenderPipelineStateCache]; } #pragma mark - MetalBuffer implementation @implementation MetalBuffer - (instancetype)initWithBuffer:(id<MTLBuffer>)buffer { if ((self = [super init])) { _buffer = buffer; _lastReuseTime = [NSDate date].timeIntervalSince1970; } return self; } @end #pragma mark - FramebufferDescriptor implementation @implementation FramebufferDescriptor - (instancetype)initWithRenderPassDescriptor:(MTLRenderPassDescriptor *)renderPassDescriptor { if ((self = [super init])) { _sampleCount = renderPassDescriptor.colorAttachments[0].texture.sampleCount; _colorPixelFormat = renderPassDescriptor.colorAttachments[0].texture.pixelFormat; _depthPixelFormat = renderPassDescriptor.depthAttachment.texture.pixelFormat; _stencilPixelFormat = renderPassDescriptor.stencilAttachment.texture.pixelFormat; } return self; } - (nonnull id)copyWithZone:(nullable NSZone *)zone { FramebufferDescriptor *copy = [[FramebufferDescriptor allocWithZone:zone] init]; copy.sampleCount = self.sampleCount; copy.colorPixelFormat = self.colorPixelFormat; copy.depthPixelFormat = self.depthPixelFormat; copy.stencilPixelFormat = self.stencilPixelFormat; return copy; } - (NSUInteger)hash { NSUInteger sc = _sampleCount & 0x3; NSUInteger cf = _colorPixelFormat & 0x3FF; NSUInteger df = _depthPixelFormat & 0x3FF; NSUInteger sf = _stencilPixelFormat & 0x3FF; NSUInteger hash = (sf << 22) | (df << 12) | (cf << 2) | sc; return hash; } - (BOOL)isEqual:(id)object { FramebufferDescriptor *other = object; if (![other isKindOfClass:[FramebufferDescriptor class]]) return NO; return other.sampleCount == self.sampleCount && other.colorPixelFormat == self.colorPixelFormat && other.depthPixelFormat == self.depthPixelFormat && other.stencilPixelFormat == self.stencilPixelFormat; } @end #pragma mark - MetalContext implementation @implementation MetalContext - (instancetype)init { if ((self = [super init])) { _renderPipelineStateCache = [NSMutableDictionary dictionary]; _bufferCache = [NSMutableArray array]; _lastBufferCachePurge = [NSDate date].timeIntervalSince1970; } return self; } - (void)makeDeviceObjectsWithDevice:(id<MTLDevice>)device { MTLDepthStencilDescriptor *depthStencilDescriptor = [[MTLDepthStencilDescriptor alloc] init]; depthStencilDescriptor.depthWriteEnabled = NO; depthStencilDescriptor.depthCompareFunction = MTLCompareFunctionAlways; self.depthStencilState = [device newDepthStencilStateWithDescriptor:depthStencilDescriptor]; } // We are retrieving and uploading the font atlas as a 4-channels RGBA texture here. // In theory we could call GetTexDataAsAlpha8() and upload a 1-channel texture to save on memory access bandwidth. // However, using a shader designed for 1-channel texture would make it less obvious to use the ImTextureID facility to render users own textures. // You can make that change in your implementation. - (void)makeFontTextureWithDevice:(id<MTLDevice>)device { ImGuiIO &io = ImGui::GetIO(); unsigned char* pixels; int width, height; io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height); MTLTextureDescriptor *textureDescriptor = [MTLTextureDescriptor texture2DDescriptorWithPixelFormat:MTLPixelFormatRGBA8Unorm width:width height:height mipmapped:NO]; textureDescriptor.usage = MTLTextureUsageShaderRead; #if TARGET_OS_OSX textureDescriptor.storageMode = MTLStorageModeManaged; #else textureDescriptor.storageMode = MTLStorageModeShared; #endif id <MTLTexture> texture = [device newTextureWithDescriptor:textureDescriptor]; [texture replaceRegion:MTLRegionMake2D(0, 0, width, height) mipmapLevel:0 withBytes:pixels bytesPerRow:width * 4]; self.fontTexture = texture; } - (MetalBuffer *)dequeueReusableBufferOfLength:(NSUInteger)length device:(id<MTLDevice>)device { NSTimeInterval now = [NSDate date].timeIntervalSince1970; // Purge old buffers that haven't been useful for a while if (now - self.lastBufferCachePurge > 1.0) { NSMutableArray *survivors = [NSMutableArray array]; for (MetalBuffer *candidate in self.bufferCache) { if (candidate.lastReuseTime > self.lastBufferCachePurge) { [survivors addObject:candidate]; } } self.bufferCache = [survivors mutableCopy]; self.lastBufferCachePurge = now; } // See if we have a buffer we can reuse MetalBuffer *bestCandidate = nil; for (MetalBuffer *candidate in self.bufferCache) if (candidate.buffer.length >= length && (bestCandidate == nil || bestCandidate.lastReuseTime > candidate.lastReuseTime)) bestCandidate = candidate; if (bestCandidate != nil) { [self.bufferCache removeObject:bestCandidate]; bestCandidate.lastReuseTime = now; return bestCandidate; } // No luck; make a new buffer id<MTLBuffer> backing = [device newBufferWithLength:length options:MTLResourceStorageModeShared]; return [[MetalBuffer alloc] initWithBuffer:backing]; } - (void)enqueueReusableBuffer:(MetalBuffer *)buffer { [self.bufferCache addObject:buffer]; } - (_Nullable id<MTLRenderPipelineState>)renderPipelineStateForFrameAndDevice:(id<MTLDevice>)device { // Try to retrieve a render pipeline state that is compatible with the framebuffer config for this frame // Thie hit rate for this cache should be very near 100%. id<MTLRenderPipelineState> renderPipelineState = self.renderPipelineStateCache[self.framebufferDescriptor]; if (renderPipelineState == nil) { // No luck; make a new render pipeline state renderPipelineState = [self _renderPipelineStateForFramebufferDescriptor:self.framebufferDescriptor device:device]; // Cache render pipeline state for later reuse self.renderPipelineStateCache[self.framebufferDescriptor] = renderPipelineState; } return renderPipelineState; } - (id<MTLRenderPipelineState>)_renderPipelineStateForFramebufferDescriptor:(FramebufferDescriptor *)descriptor device:(id<MTLDevice>)device { NSError *error = nil; NSString *shaderSource = @"" "#include <metal_stdlib>\n" "using namespace metal;\n" "\n" "struct Uniforms {\n" " float4x4 projectionMatrix;\n" "};\n" "\n" "struct VertexIn {\n" " float2 position [[attribute(0)]];\n" " float2 texCoords [[attribute(1)]];\n" " uchar4 color [[attribute(2)]];\n" "};\n" "\n" "struct VertexOut {\n" " float4 position [[position]];\n" " float2 texCoords;\n" " float4 color;\n" "};\n" "\n" "vertex VertexOut vertex_main(VertexIn in [[stage_in]],\n" " constant Uniforms &uniforms [[buffer(1)]]) {\n" " VertexOut out;\n" " out.position = uniforms.projectionMatrix * float4(in.position, 0, 1);\n" " out.texCoords = in.texCoords;\n" " out.color = float4(in.color) / float4(255.0);\n" " return out;\n" "}\n" "\n" "fragment half4 fragment_main(VertexOut in [[stage_in]],\n" " texture2d<half, access::sample> texture [[texture(0)]]) {\n" " constexpr sampler linearSampler(coord::normalized, min_filter::linear, mag_filter::linear, mip_filter::linear);\n" " half4 texColor = texture.sample(linearSampler, in.texCoords);\n" " return half4(in.color) * texColor;\n" "}\n"; id<MTLLibrary> library = [device newLibraryWithSource:shaderSource options:nil error:&error]; if (library == nil) { NSLog(@"Error: failed to create Metal library: %@", error); return nil; } id<MTLFunction> vertexFunction = [library newFunctionWithName:@"vertex_main"]; id<MTLFunction> fragmentFunction = [library newFunctionWithName:@"fragment_main"]; if (vertexFunction == nil || fragmentFunction == nil) { NSLog(@"Error: failed to find Metal shader functions in library: %@", error); return nil; } MTLVertexDescriptor *vertexDescriptor = [MTLVertexDescriptor vertexDescriptor]; vertexDescriptor.attributes[0].offset = IM_OFFSETOF(ImDrawVert, pos); vertexDescriptor.attributes[0].format = MTLVertexFormatFloat2; // position vertexDescriptor.attributes[0].bufferIndex = 0; vertexDescriptor.attributes[1].offset = IM_OFFSETOF(ImDrawVert, uv); vertexDescriptor.attributes[1].format = MTLVertexFormatFloat2; // texCoords vertexDescriptor.attributes[1].bufferIndex = 0; vertexDescriptor.attributes[2].offset = IM_OFFSETOF(ImDrawVert, col); vertexDescriptor.attributes[2].format = MTLVertexFormatUChar4; // color vertexDescriptor.attributes[2].bufferIndex = 0; vertexDescriptor.layouts[0].stepRate = 1; vertexDescriptor.layouts[0].stepFunction = MTLVertexStepFunctionPerVertex; vertexDescriptor.layouts[0].stride = sizeof(ImDrawVert); MTLRenderPipelineDescriptor *pipelineDescriptor = [[MTLRenderPipelineDescriptor alloc] init]; pipelineDescriptor.vertexFunction = vertexFunction; pipelineDescriptor.fragmentFunction = fragmentFunction; pipelineDescriptor.vertexDescriptor = vertexDescriptor; pipelineDescriptor.sampleCount = self.framebufferDescriptor.sampleCount; pipelineDescriptor.colorAttachments[0].pixelFormat = self.framebufferDescriptor.colorPixelFormat; pipelineDescriptor.colorAttachments[0].blendingEnabled = YES; pipelineDescriptor.colorAttachments[0].rgbBlendOperation = MTLBlendOperationAdd; pipelineDescriptor.colorAttachments[0].alphaBlendOperation = MTLBlendOperationAdd; pipelineDescriptor.colorAttachments[0].sourceRGBBlendFactor = MTLBlendFactorSourceAlpha; pipelineDescriptor.colorAttachments[0].sourceAlphaBlendFactor = MTLBlendFactorSourceAlpha; pipelineDescriptor.colorAttachments[0].destinationRGBBlendFactor = MTLBlendFactorOneMinusSourceAlpha; pipelineDescriptor.colorAttachments[0].destinationAlphaBlendFactor = MTLBlendFactorOneMinusSourceAlpha; pipelineDescriptor.depthAttachmentPixelFormat = self.framebufferDescriptor.depthPixelFormat; pipelineDescriptor.stencilAttachmentPixelFormat = self.framebufferDescriptor.stencilPixelFormat; id<MTLRenderPipelineState> renderPipelineState = [device newRenderPipelineStateWithDescriptor:pipelineDescriptor error:&error]; if (error != nil) { NSLog(@"Error: failed to create Metal pipeline state: %@", error); } return renderPipelineState; } - (void)emptyRenderPipelineStateCache { [self.renderPipelineStateCache removeAllObjects]; } - (void)renderDrawData:(ImDrawData *)drawData commandBuffer:(id<MTLCommandBuffer>)commandBuffer commandEncoder:(id<MTLRenderCommandEncoder>)commandEncoder { // Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer coordinates) ImGuiIO &io = ImGui::GetIO(); int fb_width = (int)(drawData->DisplaySize.x * io.DisplayFramebufferScale.x); int fb_height = (int)(drawData->DisplaySize.y * io.DisplayFramebufferScale.y); if (fb_width <= 0 || fb_height <= 0 || drawData->CmdListsCount == 0) return; drawData->ScaleClipRects(io.DisplayFramebufferScale); [commandEncoder setCullMode:MTLCullModeNone]; [commandEncoder setDepthStencilState:g_sharedMetalContext.depthStencilState]; // Setup viewport, orthographic projection matrix // Our visible imgui space lies from draw_data->DisplayPos (top left) to // draw_data->DisplayPos+data_data->DisplaySize (bottom right). DisplayMin is typically (0,0) for single viewport apps. MTLViewport viewport = { .originX = 0.0, .originY = 0.0, .width = double(fb_width), .height = double(fb_height), .znear = 0.0, .zfar = 1.0 }; [commandEncoder setViewport:viewport]; float L = drawData->DisplayPos.x; float R = drawData->DisplayPos.x + drawData->DisplaySize.x; float T = drawData->DisplayPos.y; float B = drawData->DisplayPos.y + drawData->DisplaySize.y; float N = viewport.znear; float F = viewport.zfar; const float ortho_projection[4][4] = { { 2.0f/(R-L), 0.0f, 0.0f, 0.0f }, { 0.0f, 2.0f/(T-B), 0.0f, 0.0f }, { 0.0f, 0.0f, 1/(F-N), 0.0f }, { (R+L)/(L-R), (T+B)/(B-T), N/(F-N), 1.0f }, }; [commandEncoder setVertexBytes:&ortho_projection length:sizeof(ortho_projection) atIndex:1]; size_t vertexBufferLength = 0; size_t indexBufferLength = 0; for (int n = 0; n < drawData->CmdListsCount; n++) { const ImDrawList* cmd_list = drawData->CmdLists[n]; vertexBufferLength += cmd_list->VtxBuffer.Size * sizeof(ImDrawVert); indexBufferLength += cmd_list->IdxBuffer.Size * sizeof(ImDrawIdx); } MetalBuffer *vertexBuffer = [self dequeueReusableBufferOfLength:vertexBufferLength device:commandBuffer.device]; MetalBuffer *indexBuffer = [self dequeueReusableBufferOfLength:indexBufferLength device:commandBuffer.device]; id<MTLRenderPipelineState> renderPipelineState = [self renderPipelineStateForFrameAndDevice:commandBuffer.device]; [commandEncoder setRenderPipelineState:renderPipelineState]; [commandEncoder setVertexBuffer:vertexBuffer.buffer offset:0 atIndex:0]; size_t vertexBufferOffset = 0; size_t indexBufferOffset = 0; ImVec2 pos = drawData->DisplayPos; for (int n = 0; n < drawData->CmdListsCount; n++) { const ImDrawList* cmd_list = drawData->CmdLists[n]; ImDrawIdx idx_buffer_offset = 0; memcpy((char *)vertexBuffer.buffer.contents + vertexBufferOffset, cmd_list->VtxBuffer.Data, cmd_list->VtxBuffer.Size * sizeof(ImDrawVert)); memcpy((char *)indexBuffer.buffer.contents + indexBufferOffset, cmd_list->IdxBuffer.Data, cmd_list->IdxBuffer.Size * sizeof(ImDrawIdx)); [commandEncoder setVertexBufferOffset:vertexBufferOffset atIndex:0]; for (int cmd_i = 0; cmd_i < cmd_list->CmdBuffer.Size; cmd_i++) { const ImDrawCmd* pcmd = &cmd_list->CmdBuffer[cmd_i]; if (pcmd->UserCallback) { // User callback (registered via ImDrawList::AddCallback) pcmd->UserCallback(cmd_list, pcmd); } else { ImVec4 clip_rect = ImVec4(pcmd->ClipRect.x - pos.x, pcmd->ClipRect.y - pos.y, pcmd->ClipRect.z - pos.x, pcmd->ClipRect.w - pos.y); if (clip_rect.x < fb_width && clip_rect.y < fb_height && clip_rect.z >= 0.0f && clip_rect.w >= 0.0f) { // Apply scissor/clipping rectangle MTLScissorRect scissorRect = { .x = NSUInteger(clip_rect.x), .y = NSUInteger(clip_rect.y), .width = NSUInteger(clip_rect.z - clip_rect.x), .height = NSUInteger(clip_rect.w - clip_rect.y) }; [commandEncoder setScissorRect:scissorRect]; // Bind texture, Draw if (pcmd->TextureId != NULL) [commandEncoder setFragmentTexture:(__bridge id<MTLTexture>)(pcmd->TextureId) atIndex:0]; [commandEncoder drawIndexedPrimitives:MTLPrimitiveTypeTriangle indexCount:pcmd->ElemCount indexType:sizeof(ImDrawIdx) == 2 ? MTLIndexTypeUInt16 : MTLIndexTypeUInt32 indexBuffer:indexBuffer.buffer indexBufferOffset:indexBufferOffset + idx_buffer_offset]; } } idx_buffer_offset += pcmd->ElemCount * sizeof(ImDrawIdx); } vertexBufferOffset += cmd_list->VtxBuffer.Size * sizeof(ImDrawVert); indexBufferOffset += cmd_list->IdxBuffer.Size * sizeof(ImDrawIdx); } __weak id weakSelf = self; [commandBuffer addCompletedHandler:^(id<MTLCommandBuffer>) { dispatch_async(dispatch_get_main_queue(), ^{ [weakSelf enqueueReusableBuffer:vertexBuffer]; [weakSelf enqueueReusableBuffer:indexBuffer]; }); }]; } @end