Examples: Comments + shallow coding convention tweak to be consistent across examples and with imgui_impl_osx

examples/README.txt

@@ -166,12 +166,12 @@ example_win32_directx12/
 example_apple_metal/
     OSX & iOS + Metal.
     It is based on the "cross-platform" game template provided with Xcode as of Xcode 9.
-    Note that instead of the OSX bindings, you may want to use GLFW or SDL which will also support Windows, Linux along with OSX.
+    (NB: you may still want to use GLFW or SDL which will also support Windows, Linux along with OSX.)
     = game template + imgui_impl_osx.mm + imgui_impl_metal.mm
 
 example_apple_opengl2/
     OSX + OpenGL2.
-    Note that instead of the OSX bindings, you may want to use GLFW or SDL which will also support Windows, Linux along with OSX.
+    (NB: you may still want to use GLFW or SDL which will also support Windows, Linux along with OSX.)
     = main.mm + imgui_impl_osx.mm + imgui_impl_opengl2.cpp
 
 example_glfw_opengl2/

examples/example_apple_metal/README.md

@@ -2,5 +2,7 @@
 
 ## Introduction
 
-This example shows how to render ImGui with Metal. It is based on the cross-platform game template provided with Xcode as of Xcode 9.
+This example shows how to integrate Dear ImGui with Metal. It is based on the "cross-platform" game template provided with Xcode as of Xcode 9.
+
+(NB: you may still want to use GLFW or SDL which will also support Windows, Linux along with OSX.)
 

examples/imgui_impl_metal.mm

@@ -128,8 +128,10 @@ void ImGui_ImplMetal_DestroyDeviceObjects()
 #pragma mark - MetalBuffer implementation
 
 @implementation MetalBuffer
-- (instancetype)initWithBuffer:(id<MTLBuffer>)buffer {
+- (instancetype)initWithBuffer:(id<MTLBuffer>)buffer 
-    if ((self = [super init])) {
+{
+    if ((self = [super init])) 
+    {
         _buffer = buffer;
         _lastReuseTime = [NSDate date].timeIntervalSince1970;
     }
@@ -140,8 +142,10 @@ void ImGui_ImplMetal_DestroyDeviceObjects()
 #pragma mark - FramebufferDescriptor implementation
 
 @implementation FramebufferDescriptor
-- (instancetype)initWithRenderPassDescriptor:(MTLRenderPassDescriptor *)renderPassDescriptor {
+- (instancetype)initWithRenderPassDescriptor:(MTLRenderPassDescriptor *)renderPassDescriptor 
-    if ((self = [super init])) {
+{
+    if ((self = [super init])) 
+    {
         _sampleCount = renderPassDescriptor.colorAttachments[0].texture.sampleCount;
         _colorPixelFormat = renderPassDescriptor.colorAttachments[0].texture.pixelFormat;
         _depthPixelFormat = renderPassDescriptor.depthAttachment.texture.pixelFormat;
@@ -150,7 +154,8 @@ void ImGui_ImplMetal_DestroyDeviceObjects()
     return self;
 }
 
-- (nonnull id)copyWithZone:(nullable NSZone *)zone {
+- (nonnull id)copyWithZone:(nullable NSZone *)zone 
+{
     FramebufferDescriptor *copy = [[FramebufferDescriptor allocWithZone:zone] init];
     copy.sampleCount = self.sampleCount;
     copy.colorPixelFormat = self.colorPixelFormat;
@@ -159,7 +164,8 @@ void ImGui_ImplMetal_DestroyDeviceObjects()
     return copy;
 }
 
-- (NSUInteger)hash {
+- (NSUInteger)hash 
+{
     NSUInteger sc = _sampleCount & 0x3;
     NSUInteger cf = _colorPixelFormat & 0x3FF;
     NSUInteger df = _depthPixelFormat & 0x3FF;
@@ -168,12 +174,12 @@ void ImGui_ImplMetal_DestroyDeviceObjects()
     return hash;
 }
 
-- (BOOL)isEqual:(id)object {
+- (BOOL)isEqual:(id)object 
+{
     FramebufferDescriptor *other = object;
-    if (![other isKindOfClass:[FramebufferDescriptor class]]) {
+    if (![other isKindOfClass:[FramebufferDescriptor class]])
         return NO;
-    }
+    return other.sampleCount == self.sampleCount      &&
-    return other.sampleCount        == self.sampleCount      &&
     other.colorPixelFormat   == self.colorPixelFormat &&
     other.depthPixelFormat   == self.depthPixelFormat &&
     other.stencilPixelFormat == self.stencilPixelFormat;
@@ -185,7 +191,8 @@ void ImGui_ImplMetal_DestroyDeviceObjects()
 
 @implementation MetalContext
 - (instancetype)init {
-    if ((self = [super init])) {
+    if ((self = [super init])) 
+    {
         _renderPipelineStateCache = [NSMutableDictionary dictionary];
         _bufferCache = [NSMutableArray array];
         _lastBufferCachePurge = [NSDate date].timeIntervalSince1970;
@@ -193,14 +200,20 @@ void ImGui_ImplMetal_DestroyDeviceObjects()
     return self;
 }
 
-- (void)makeDeviceObjectsWithDevice:(id<MTLDevice>)device {
+- (void)makeDeviceObjectsWithDevice:(id<MTLDevice>)device 
+{
     MTLDepthStencilDescriptor *depthStencilDescriptor = [[MTLDepthStencilDescriptor alloc] init];
     depthStencilDescriptor.depthWriteEnabled = NO;
     depthStencilDescriptor.depthCompareFunction = MTLCompareFunctionAlways;
     self.depthStencilState = [device newDepthStencilStateWithDescriptor:depthStencilDescriptor];
 }
 
-- (void)makeFontTextureWithDevice:(id<MTLDevice>)device {
+// 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;
@@ -220,14 +233,18 @@ void ImGui_ImplMetal_DestroyDeviceObjects()
     self.fontTexture = texture;
 }
 
-- (MetalBuffer *)dequeueReusableBufferOfLength:(NSUInteger)length device:(id<MTLDevice>)device {
+- (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) {
+    if (now - self.lastBufferCachePurge > 1.0) 
+    {
         NSMutableArray *survivors = [NSMutableArray array];
-        for (MetalBuffer *candidate in self.bufferCache) {
+        for (MetalBuffer *candidate in self.bufferCache) 
-            if (candidate.lastReuseTime > self.lastBufferCachePurge) {
+        {
+            if (candidate.lastReuseTime > self.lastBufferCachePurge) 
+            {
                 [survivors addObject:candidate];
             }
         }
@@ -237,13 +254,12 @@ void ImGui_ImplMetal_DestroyDeviceObjects()
     
     // See if we have a buffer we can reuse
     MetalBuffer *bestCandidate = nil;
-    for (MetalBuffer *candidate in self.bufferCache) {
+    for (MetalBuffer *candidate in self.bufferCache) 
-        if (candidate.buffer.length >= length && (bestCandidate == nil || bestCandidate.lastReuseTime > candidate.lastReuseTime)) {
+        if (candidate.buffer.length >= length && (bestCandidate == nil || bestCandidate.lastReuseTime > candidate.lastReuseTime))
             bestCandidate = candidate;
-        }
-    }
     
-    if (bestCandidate != nil) {
+    if (bestCandidate != nil) 
+    {
         [self.bufferCache removeObject:bestCandidate];
         bestCandidate.lastReuseTime = now;
         return bestCandidate;
@@ -254,16 +270,19 @@ void ImGui_ImplMetal_DestroyDeviceObjects()
     return [[MetalBuffer alloc] initWithBuffer:backing];
 }
 
-- (void)enqueueReusableBuffer:(MetalBuffer *)buffer {
+- (void)enqueueReusableBuffer:(MetalBuffer *)buffer 
+{
     [self.bufferCache addObject:buffer];
 }
 
-- (_Nullable id<MTLRenderPipelineState>)renderPipelineStateForFrameAndDevice:(id<MTLDevice>)device {
+- (_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) {
+    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
@@ -314,7 +333,8 @@ void ImGui_ImplMetal_DestroyDeviceObjects()
     "}\n";
     
     id<MTLLibrary> library = [device newLibraryWithSource:shaderSource options:nil error:&error];
-    if (library == nil) {
+    if (library == nil) 
+    {
         NSLog(@"Error: failed to create Metal library: %@", error);
         return nil;
     }
@@ -322,7 +342,8 @@ void ImGui_ImplMetal_DestroyDeviceObjects()
     id<MTLFunction> vertexFunction = [library newFunctionWithName:@"vertex_main"];
     id<MTLFunction> fragmentFunction = [library newFunctionWithName:@"fragment_main"];
     
-    if (vertexFunction == nil || fragmentFunction == nil) {
+    if (vertexFunction == nil || fragmentFunction == nil) 
+    {
         NSLog(@"Error: failed to find Metal shader functions in library: %@", error);
         return nil;
     }
@@ -358,14 +379,16 @@ void ImGui_ImplMetal_DestroyDeviceObjects()
     pipelineDescriptor.stencilAttachmentPixelFormat = self.framebufferDescriptor.stencilPixelFormat;
     
     id<MTLRenderPipelineState> renderPipelineState = [device newRenderPipelineStateWithDescriptor:pipelineDescriptor error:&error];
-    if (error != nil) {
+    if (error != nil) 
+    {
         NSLog(@"Error: failed to create Metal pipeline state: %@", error);
     }
     
     return renderPipelineState;
 }
 
-- (void)emptyRenderPipelineStateCache {
+- (void)emptyRenderPipelineStateCache 
+{
     [self.renderPipelineStateCache removeAllObjects];
 }
 
@@ -387,12 +410,15 @@ void ImGui_ImplMetal_DestroyDeviceObjects()
     // Setup viewport, orthographic projection matrix
     // Our visible imgui space lies from draw_data->DisplayPps (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,
+    MTLViewport viewport = 
+    {   
+        .originX = 0.0,
         .originY = 0.0,
         .width = double(fb_width),
         .height = double(fb_height),
         .znear = 0.0,
-        .zfar = 1.0 };
+        .zfar = 1.0 
+    };
     [commandEncoder setViewport:viewport];
     float L = drawData->DisplayPos.x;
     float R = drawData->DisplayPos.x + drawData->DisplaySize.x;
@@ -412,7 +438,8 @@ void ImGui_ImplMetal_DestroyDeviceObjects()
     
     size_t vertexBufferLength = 0;
     size_t indexBufferLength = 0;
-    for (int n = 0; n < drawData->CmdListsCount; n++) {
+    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);
@@ -461,9 +488,8 @@ void ImGui_ImplMetal_DestroyDeviceObjects()
                     
                     
                     // Bind texture, Draw
-                    if (pcmd->TextureId != NULL) {
+                    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
@@ -479,7 +505,8 @@ void ImGui_ImplMetal_DestroyDeviceObjects()
     }
     
     __weak id weakSelf = self;
-    [commandBuffer addCompletedHandler:^(id<MTLCommandBuffer>) {
+    [commandBuffer addCompletedHandler:^(id<MTLCommandBuffer>) 
+    {
         dispatch_async(dispatch_get_main_queue(), ^{
             [weakSelf enqueueReusableBuffer:vertexBuffer];
             [weakSelf enqueueReusableBuffer:indexBuffer];