v/renderer/metal/metal.cpp

//
// Created by Vicente Ferrari Smith on 26.02.26.
//

#include "init.h"
#include "../graphics.h"
#include <print>
#include <iostream>
#include <fstream>
#include <GLFW/glfw3.h>
#define GLFW_EXPOSE_NATIVE_COCOA
#include <GLFW/glfw3native.h>
#include <objc/message.h>
#include <objc/objc.h>
#include "vertex_data.h"

Device metal_device{};
MTL::Buffer* triangle_vertex_buffer{};
MTL::CommandQueue *queue{};
CA::MetalLayer *metal_layer{};
MTL::RenderPipelineState *pipeline_state{};
CA::MetalDrawable *metal_drawable{};
MTL::CommandBuffer* metal_command_buffer{};

MTL::Function *vertex_shader{};
MTL::Function *fragment_shader{};

void create_window(GLFWwindow *window) {
    void *ns_window = glfwGetCocoaWindow(window);
    if (!ns_window) {
        throw std::runtime_error("Failed to get Cocoa window from GLFWwindow");
    }

    SEL contentViewSel = sel_registerName("contentView");
    id content_view = ((id (*)(id, SEL))objc_msgSend)((id)ns_window, contentViewSel);

    SEL setWantsLayerSel = sel_registerName("setWantsLayer:");
    ((void (*)(id, SEL, bool))objc_msgSend)(content_view, setWantsLayerSel, true);

    metal_layer = CA::MetalLayer::layer()->retain();

    SEL setLayerSel = sel_registerName("setLayer:");
    ((void (*)(id, SEL, id))objc_msgSend)(content_view, setLayerSel, (id)metal_layer);

    metal_layer->retain();
    metal_layer->setDevice(metal_device.device);
    metal_layer->setPixelFormat(MTL::PixelFormatRGBA16Float);
    metal_layer->setFramebufferOnly(true);
    metal_layer->setDrawableSize(CGSizeMake(800, 600));
    CGColorSpaceRef p3Space = CGColorSpaceCreateWithName(kCGColorSpaceSRGB);
    metal_layer->setColorspace(p3Space);
}

void encode_render_command(MTL::RenderCommandEncoder *renderCommandEncoder) {
    renderCommandEncoder->setRenderPipelineState(pipeline_state);
    renderCommandEncoder->setVertexBuffer(triangle_vertex_buffer, 0, 0);
    MTL::PrimitiveType typeTriangle = MTL::PrimitiveTypeTriangle;
    NS::UInteger vertexStart = 0;
    NS::UInteger vertexCount = 6;
    renderCommandEncoder->drawPrimitives(typeTriangle, vertexStart, vertexCount);
}

void send_render_command() {
    metal_command_buffer = queue->commandBuffer();

    MTL::RenderPassDescriptor* renderPassDescriptor = MTL::RenderPassDescriptor::alloc()->init();
    MTL::RenderPassColorAttachmentDescriptor *cd = renderPassDescriptor->colorAttachments()->object(0);
    cd->setTexture(metal_drawable->texture());
    cd->setLoadAction(MTL::LoadActionClear);
    cd->setClearColor(MTL::ClearColor(
        100.0f / 255.0f,
        149.0f / 255.0f,
        237.0f / 255.0f,
        1.0
        ));
    cd->setStoreAction(MTL::StoreActionStore);

    MTL::RenderCommandEncoder* renderCommandEncoder = metal_command_buffer->renderCommandEncoder(renderPassDescriptor);
    encode_render_command(renderCommandEncoder);
    renderCommandEncoder->endEncoding();

    metal_command_buffer->presentDrawable(metal_drawable);
    metal_command_buffer->commit();
    metal_command_buffer->waitUntilCompleted();

    renderPassDescriptor->release();
}

void LoadMetalShader(const std::string &shader_path,
                     const std::string &vertex_fn_name,
                     const std::string &fragment_fn_name)
{
    NS::Error *error = nullptr;
    MTL::Library *library = nullptr;

    auto ends_with = [](const std::string& s, const char* suf) -> bool {
        const size_t n = std::strlen(suf);
        return s.size() >= n && s.compare(s.size() - n, n, suf) == 0;
    };

    if (ends_with(shader_path, ".metal")) {
        // Compile from source at runtime
        std::ifstream file(shader_path, std::ios::in | std::ios::binary);
        if (!file.is_open()) {
            throw std::runtime_error("Failed to open .metal source file");
        }
        std::string src;
        file.seekg(0, std::ios::end);
        src.resize(static_cast<size_t>(file.tellg()));
        file.seekg(0, std::ios::beg);
        file.read(src.data(), static_cast<std::streamsize>(src.size()));
        file.close();

        NS::String* source = NS::String::string(src.c_str(), NS::UTF8StringEncoding);
        MTL::CompileOptions* opts = MTL::CompileOptions::alloc()->init();
        library = metal_device.device->newLibrary(source, opts, &error);
        opts->release();
    } else {
        // Load a precompiled metallib from file path
        NS::String *nsPath = NS::String::string(shader_path.c_str(), NS::UTF8StringEncoding);
        library = metal_device.device->newLibrary(nsPath, &error);
    }

    if (error || library == nullptr) {
        if (error) {
            // Extract the actual compiler error message
            const char* errorMessage = error->localizedDescription()->utf8String();
            std::string detailedError = "Metal Library Error: ";
            detailedError += errorMessage;

            // It is good practice to release the error object if it exists
            error->release();

            throw std::runtime_error(detailedError);
        }
        throw std::runtime_error("Failed to create Metal library (Unknown error)");
    }
    NS::String *vname = NS::String::string(vertex_fn_name.c_str(), NS::UTF8StringEncoding);
    NS::String *fname = NS::String::string(fragment_fn_name.c_str(), NS::UTF8StringEncoding);
    vertex_shader = library->newFunction(vname);
    fragment_shader = library->newFunction(fname);

    if (vertex_shader == nullptr || fragment_shader == nullptr) {
        throw std::runtime_error("Failed to create Metal shader functions");
    }

    library->release();
}

void create_render_pipeline() {
    LoadMetalShader("shaders/shader.metal", "vertex_main", "fragment_main");

    MTL::RenderPipelineDescriptor* renderPipelineDescriptor = MTL::RenderPipelineDescriptor::alloc()->init();
    renderPipelineDescriptor->setLabel(NS::String::string("Triangle Rendering Pipeline", NS::ASCIIStringEncoding));
    renderPipelineDescriptor->setVertexFunction(vertex_shader);
    renderPipelineDescriptor->setFragmentFunction(fragment_shader);
    assert(renderPipelineDescriptor);
    const MTL::PixelFormat pixel_format = metal_layer->pixelFormat();
    renderPipelineDescriptor->colorAttachments()->object(0)->setPixelFormat(pixel_format);

    NS::Error* error;
    pipeline_state = metal_device.device->newRenderPipelineState(renderPipelineDescriptor, &error);
    renderPipelineDescriptor->release();
}

void create_command_queue() {
    queue = metal_device.device->newCommandQueue();
}

void create_triangle() {
    VertexData square_vertices[] = {
        {{-0.5, -0.5}, {1.0, 0.0, 0.0, 1.0}},
        {{0.5, -0.5}, {0.0, 1.0, 0.0, 1.0}},
        {{0.5, 0.5}, {0.0, 0.0, 1.0, 1.0}},

        {{0.5, 0.5}, {0.0, 0.0, 1.0, 1.0}},
        {{-0.5, 0.5}, {0.0, 1.0, 0.0, 1.0}},
        {{-0.5, -0.5}, {1.0, 0.0, 0.0, 1.0}},
    };

    triangle_vertex_buffer = metal_device.device->newBuffer(&square_vertices,
                                                  sizeof(square_vertices),
                                                  MTL::ResourceStorageModeShared);

}

void graphics_init(GLFWwindow *window) {
    std::println("wow, we are on macos!! crazy!!");

    create_device();
    create_window(window);
    create_triangle();
    create_command_queue();
    create_render_pipeline();
}

void graphics_deinit() {

}

void begin_frame() {

}

void end_frame() {
    auto pPool = NS::AutoreleasePool::alloc()->init();
    metal_drawable = metal_layer->nextDrawable();

    send_render_command();

    pPool->release();
}

void create_device() {
    metal_device.device = MTL::CreateSystemDefaultDevice();
}