Added an example to showcase the metal backend

Author: nullcatalyst

.gitignore

@@ -1,5 +1,6 @@
 # Project
 build/
+build_*/
 tmp/
 
 # Compiled Object files

CMakeLists.txt

@@ -9,8 +9,10 @@ if(NOT CMAKE_BUILD_TYPE)
     set(CMAKE_BUILD_TYPE Release)
 endif()
 
-option(BACKEND_METAL    "Build the Metal backend"   ON)
-option(BACKEND_OPENGL   "Build the OpenGL backend"  OFF)
+option(BACKEND_METAL    "Build the Metal backend"       ON)
+option(BACKEND_OPENGL   "Build the OpenGL backend"      OFF)
+
+option(BUILD_EXAMPLES   "Build the example projects"    ON)
 
 # TARGET
 
@@ -31,6 +33,11 @@ if(BACKEND_METAL)
         "-fobjc-arc"
     )
 
+    target_compile_definitions(graphics
+    PUBLIC
+        GRAPHICS_USE_METAL=1
+    )
+
     target_sources(graphics
     PRIVATE
         src/graphics/metal/context.mm
@@ -44,8 +51,21 @@ if(BACKEND_METAL)
 endif()
 
 if(BACKEND_OPENGL)
+    target_compile_definitions(graphics
+    PUBLIC
+        GRAPHICS_USE_OPENGL=1
+    )
+
     target_sources(graphics
     PRIVATE
         # src/graphics/opengl/*
     )
 endif()
+
+# EXAMPLES
+
+if(BUILD_EXAMPLES)
+    if(BACKEND_METAL)
+        add_subdirectory(examples/hello_metal)
+    endif()
+endif()

examples/hello_metal/AppDelegate.h

@@ -0,0 +1,5 @@
+#import <Cocoa/Cocoa.h>
+
+@interface AppDelegate : NSObject <NSApplicationDelegate, NSWindowDelegate>
+
+@end

examples/hello_metal/AppDelegate.mm

@@ -0,0 +1,60 @@
+#import "./AppDelegate.h"
+#import "./Renderer.h"
+
+@implementation AppDelegate {
+    NSString *  _appName;
+    NSWindow *  _window;
+    Renderer *  _renderer;
+}
+
+- (nonnull instancetype) init {
+    if ((self = [super init])) {
+        _appName = [[NSProcessInfo processInfo] processName];
+
+        NSApplication * application = [NSApplication sharedApplication];
+        [application setMainMenu:[self createMenu]];
+        _window = [self createWindow];
+    }
+
+    return self;
+}
+
+- (void) applicationWillFinishLaunching:(NSNotification *)notification {
+    [_window setTitle:_appName];
+    [_window cascadeTopLeftFromPoint:NSMakePoint(20, 20)];
+    [_window makeKeyAndOrderFront:self];
+}
+
+- (BOOL) applicationShouldTerminateAfterLastWindowClosed:(NSApplication *)sender {
+    return TRUE;
+}
+
+- (NSMenu *) createMenu {
+    NSMenuItem * quit   = [[NSMenuItem alloc] initWithTitle:[@"Quit " stringByAppendingString:_appName] action:@selector(terminate:) keyEquivalent:@"q"];
+    NSMenuItem * item   = [[NSMenuItem alloc] init];
+    item.submenu        = [[NSMenu alloc] init];
+    [item.submenu addItem:quit];
+
+    NSMenu * mainMenu   = [[NSMenu alloc] init];
+    [mainMenu addItem:item];
+
+    return mainMenu;
+}
+
+- (NSWindow *) createWindow {
+    NSWindow * window = [[NSWindow alloc] initWithContentRect:NSMakeRect(0, 0, 640, 480)
+                                                    styleMask:NSWindowStyleMaskTitled | NSWindowStyleMaskClosable
+                                                      backing:NSBackingStoreBuffered
+                                                        defer:NO];
+
+    MTKView * mtlView = [[MTKView alloc] initWithFrame:window.contentView.frame device:MTLCreateSystemDefaultDevice()];
+    [window.contentView addSubview:mtlView];
+
+    _renderer = [[Renderer alloc] initWithMetalKitView:mtlView];
+    [_renderer mtkView:mtlView drawableSizeWillChange:mtlView.drawableSize];
+    mtlView.delegate = _renderer;
+
+    return window;
+}
+
+@end

examples/hello_metal/CMakeLists.txt

@@ -0,0 +1,44 @@
+cmake_minimum_required(VERSION 3.10)
+
+if(NOT XCODE)
+    message(
+    WARNING
+        "Cannot create `hello_metal` example: The generator must be `Xcode` in order to compile metal shader files"
+    )
+else()
+    project(hello_metal)
+    set(CMAKE_CXX_STANDARD 17)
+
+    add_executable(hello_metal)
+
+    target_compile_options(hello_metal
+    PUBLIC
+        "-fobjc-arc"
+    )
+
+    set(SHADERS
+        shader.metal
+    )
+
+    set_source_files_properties(
+        ${SHADERS}
+    PROPERTIES
+        LANGUAGE METAL
+    )
+
+    target_sources(hello_metal
+    PRIVATE
+        main.mm
+        AppDelegate.mm
+        Renderer.mm
+        ${SHADERS}
+    )
+
+    target_link_libraries(hello_metal
+    PRIVATE
+        graphics
+        "-framework Cocoa"
+        "-framework Metal"
+        "-framework MetalKit"
+    )
+endif()

examples/hello_metal/Renderer.h

@@ -0,0 +1,7 @@
+#import <MetalKit/MetalKit.h>
+
+@interface Renderer : NSObject <MTKViewDelegate>
+
+- (nonnull instancetype) initWithMetalKitView:(nonnull MTKView *)view;
+
+@end

examples/hello_metal/Renderer.mm

@@ -0,0 +1,41 @@
+#import "./Renderer.h"
+
+#include <simd/simd.h>
+#include <graphics/graphics.hpp>
+
+#define SIZEOF_ARRAY(array) (sizeof(array) / sizeof(*array))
+
+// Declare the graphics data used for initialization
+#include "../shared/decl.inc"
+
+@implementation Renderer {
+    graphics::Context *         _context;
+    graphics::State *           _state;
+    graphics::DynamicBuffer *   _uniformsBuffer;
+    graphics::StaticBuffer *    _verticesBuffer;
+}
+
+- (nonnull instancetype) initWithMetalKitView:(nonnull MTKView *)view {
+    if ((self = [super init])) {
+        _context = new graphics::Context(view);
+
+        // Initialize the graphics objects
+        #include "../shared/init.inc"
+    }
+
+    return self;
+}
+
+- (void) drawInMTKView:(nonnull MTKView *)view {
+    // Render the frame
+    #include "../shared/update.inc"
+
+    // Render the frame
+    #include "../shared/render.inc"
+}
+
+- (void) mtkView:(nonnull MTKView *)view drawableSizeWillChange:(CGSize)size {
+    // Respond to drawable size or orientation changes here
+}
+
+@end

examples/hello_metal/main.mm

@@ -0,0 +1,17 @@
+#import <Cocoa/Cocoa.h>
+
+#import "./AppDelegate.h"
+
+int main() {
+    @autoreleasepool {
+        NSApplication * application = [NSApplication sharedApplication];
+        [application setActivationPolicy:NSApplicationActivationPolicyRegular];
+
+        AppDelegate * appDelegate = [[AppDelegate alloc] init];
+        [application setDelegate:appDelegate];
+        [application activateIgnoringOtherApps:YES];
+        [application run];
+    }
+
+    return EXIT_SUCCESS;
+}

examples/hello_metal/shader.metal

@@ -0,0 +1,27 @@
+#include <metal_stdlib>
+using namespace metal;
+
+struct Vertex {
+    float4      position    [[ attribute(0) ]];
+    float4      color       [[ attribute(1) ]];
+};
+
+struct Uniforms {
+    float4x4    matrix;
+};
+
+struct InOut {
+    float4 position [[ position ]];
+    half4 color;
+};
+
+vertex InOut default_vertex(Vertex in [[ stage_in ]], constant Uniforms & uniforms [[ buffer(1) ]]) {
+    InOut out;
+    out.position = uniforms.matrix * in.position;
+    out.color = half4(in.color);
+    return out;
+}
+
+fragment half4 default_fragment(InOut in [[ stage_in ]]) {
+    return in.color;
+}

examples/shared/decl.inc

@@ -0,0 +1,56 @@
+struct Vertex {
+    simd::float4 position;
+    simd::float4 color;
+};
+
+struct Uniforms {
+    simd::float4x4 matrix;
+};
+
+const Vertex VERTICES[] = {
+    Vertex{ simd::float4{-0.5f, -0.5f, 0.0f, 1.0f}, simd::float4{1.0f, 0.0f, 0.0f, 1.0f} },
+    Vertex{ simd::float4{+0.5f, -0.5f, 0.0f, 1.0f}, simd::float4{1.0f, 1.0f, 0.0f, 1.0f} },
+    Vertex{ simd::float4{-0.5f, +0.5f, 0.0f, 1.0f}, simd::float4{0.0f, 0.0f, 1.0f, 1.0f} },
+    Vertex{ simd::float4{+0.5f, +0.5f, 0.0f, 1.0f}, simd::float4{0.0f, 1.0f, 0.0f, 1.0f} },
+};
+
+const graphics::VertexAttribute VERTEX_ATTRIBS[] = {
+    graphics::VertexAttribute{
+        .id             = 0,
+        .format         = graphics::VertexFormat::Float4,
+        .offset         = offsetof(Vertex, position),
+        .bufferIndex    = 0,
+    },
+    graphics::VertexAttribute{
+        .id             = 1,
+        .format         = graphics::VertexFormat::Float4,
+        .offset         = offsetof(Vertex, color),
+        .bufferIndex    = 0,
+    },
+};
+
+const graphics::BufferLayout VERTEX_LAYOUTS[] = {
+    graphics::BufferLayout{
+        .bufferIndex    = 0,
+        .stride         = sizeof(Vertex),
+        .stepFunction   = graphics::StepFunction::PerVertex,
+    },
+};
+
+const graphics::VertexDesc VERTEX_DESC{
+    .attributeCount = SIZEOF_ARRAY(VERTEX_ATTRIBS),
+    .layoutCount    = SIZEOF_ARRAY(VERTEX_LAYOUTS),
+    .attributes     = VERTEX_ATTRIBS,
+    .layouts        = VERTEX_LAYOUTS,
+};
+
+const graphics::StateDesc stateDesc{
+    .vertexShader           = "default_vertex",
+    .fragmentShader         = "default_fragment",
+    .targetDesc             = nullptr, //< Use screen
+    .vertexDesc             = &VERTEX_DESC,
+    .cullMode               = graphics::CullMode::Back,
+    .winding                = graphics::Winding::CounterClockwise,
+    .depthCompareFunction   = graphics::CompareFunction::Always,
+    .depthWriteEnabled      = true,
+};

examples/shared/init.inc

@@ -0,0 +1,4 @@
+_state = _context->createState(stateDesc);
+
+_uniformsBuffer = _context->createDynamicBuffer<Uniforms>(1);
+_verticesBuffer = _context->createStaticBuffer(SIZEOF_ARRAY(VERTICES), VERTICES);

examples/shared/render.inc

@@ -0,0 +1,17 @@
+_context->startFrame();
+
+    // Render to the screen
+    _context->setRenderTarget(nullptr);
+
+    // Set the graphics state
+    // This includes the shaders, depth and blend settings
+    _context->setState(_state);
+
+    // Set the buffers to use to render
+    _context->setBuffer(0, _verticesBuffer);
+    _context->setBuffer(1, _uniformsBuffer);
+
+    // Finally draw the triangles
+    _context->drawTriangleStrip(SIZEOF_ARRAY(VERTICES));
+
+_context->commitFrame();

examples/shared/update.inc

@@ -0,0 +1,17 @@
+static float angle = 0.0f;
+angle += 0.5f * M_PI / 60.0f;
+
+const uint32_t frame = _context->getFrame();
+
+float c = cosf(angle);
+float s = sinf(angle);
+
+Uniforms * uniforms = (Uniforms *) _uniformsBuffer->getData(frame);
+uniforms->matrix = simd::float4x4{
+    simd::float4{    c,    s, 0.0f, 0.0f },
+    simd::float4{   -s,    c, 0.0f, 0.0f },
+    simd::float4{ 0.0f, 0.0f, 1.0f, 0.0f },
+    simd::float4{ 0.0f, 0.0f, 0.0f, 1.0f },
+};
+
+_uniformsBuffer->update(frame);

include/graphics/descriptors.hpp

@@ -71,7 +71,6 @@ namespace graphics {
     struct BufferLayout {
         uint32_t                bufferIndex;
         uint32_t                stride;
-        uint32_t                stepRate;
         StepFunction            stepFunction;
     };
 

include/graphics/graphics.hpp

@@ -14,12 +14,16 @@
 
 #if GRAPHICS_USE_METAL
     #include "graphics/metal/context.hpp"
-    namespace graphics = graphics::metal;
+    namespace graphics {
+        using namespace metal;
+    }
 #endif
 
 #if GRAPHICS_USE_OPENGL
     #include "graphics/opengl/graphics.hpp"
-    namespace graphics = graphics::opengl;
+    namespace graphics {
+        using namespace opengl;
+    }
 #endif
 
 #endif /* graphics_graphics_hpp */