GHOST_ContextCGL.mm

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/* SPDX-FileCopyrightText: 2013 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */

 
/* Don't generate OpenGL deprecation warning. This is a known thing, and is not something easily
 * solvable in a short term. */
#ifdef __clang__
#  pragma clang diagnostic ignored "-Wdeprecated-declarations"
#endif
 
#include "GHOST_ContextCGL.hh"
 
#import <Cocoa/Cocoa.h>
#import <Metal/Metal.h>
#import <QuartzCore/QuartzCore.h>
 
#include <cassert>
#include <vector>
 
static const MTLPixelFormat METAL_FRAMEBUFFERPIXEL_FORMAT_EDR = MTLPixelFormatRGBA16Float;
 
static void ghost_fatal_error_dialog(const char *msg)
{
  @autoreleasepool {
    NSString *message = [NSString stringWithFormat:@"Error opening window:\n%s", msg];
 
    NSAlert *alert = [[NSAlert alloc] init];
 
    alert.messageText = @"Blender";
    alert.informativeText = message;
    alert.alertStyle = NSAlertStyleCritical;
 
    [alert addButtonWithTitle:@"Quit"];
    [alert runModal];
  }
 
  exit(1);
}
 
MTLCommandQueue *GHOST_ContextCGL::s_sharedMetalCommandQueue = nil;
int GHOST_ContextCGL::s_sharedCount = 0;
 
GHOST_ContextCGL::GHOST_ContextCGL(bool stereoVisual,
                                   NSView *metalView,
                                   CAMetalLayer *metalLayer,
                                   int debug)
    : GHOST_Context(stereoVisual),
      m_metalView(metalView),
      m_metalLayer(metalLayer),
      m_metalRenderPipeline(nil),
      m_debug(debug)
{
  @autoreleasepool {
    /* Initialize Metal Swap-chain. */
    current_swapchain_index = 0;
    for (int i = 0; i < METAL_SWAPCHAIN_SIZE; i++) {
      m_defaultFramebufferMetalTexture[i].texture = nil;
      m_defaultFramebufferMetalTexture[i].index = i;
    }
 
    if (m_metalView) {
      m_ownsMetalDevice = false;
      metalInit();
    }
    else {
      /* Prepare offscreen GHOST Context Metal device. */
      id<MTLDevice> metalDevice = MTLCreateSystemDefaultDevice();
 
      if (m_debug) {
        printf("Selected Metal Device: %s\n", [metalDevice.name UTF8String]);
      }
 
      m_ownsMetalDevice = true;
      if (metalDevice) {
        m_metalLayer = [[CAMetalLayer alloc] init];
        m_metalLayer.edgeAntialiasingMask = 0;
        m_metalLayer.masksToBounds = NO;
        m_metalLayer.opaque = YES;
        m_metalLayer.framebufferOnly = YES;
        m_metalLayer.presentsWithTransaction = NO;
        [m_metalLayer removeAllAnimations];
        m_metalLayer.device = metalDevice;
        m_metalLayer.allowsNextDrawableTimeout = NO;
 
        /* Enable EDR support. This is done by:
         * 1. Using a floating point render target, so that values outside 0..1 can be used
         * 2. Informing the OS that we are EDR aware, and intend to use values outside 0..1
         * 3. Setting the extended sRGB color space so that the OS knows how to interpret the
         *    values.
         */
        m_metalLayer.wantsExtendedDynamicRangeContent = YES;
        m_metalLayer.pixelFormat = METAL_FRAMEBUFFERPIXEL_FORMAT_EDR;
        const CFStringRef name = kCGColorSpaceExtendedSRGB;
        CGColorSpaceRef colorspace = CGColorSpaceCreateWithName(name);
        m_metalLayer.colorspace = colorspace;
        CGColorSpaceRelease(colorspace);
 
        metalInit();
      }
      else {
        ghost_fatal_error_dialog(
            "[ERROR] Failed to create Metal device for offscreen GHOST Context.\n");
      }
    }
 
    /* Initialize swap-interval. */
    mtl_SwapInterval = 60;
  }
}
 
GHOST_ContextCGL::~GHOST_ContextCGL()
{
  metalFree();
 
  if (m_ownsMetalDevice) {
    if (m_metalLayer) {
      [m_metalLayer release];
      m_metalLayer = nil;
    }
  }
  assert(s_sharedCount);
 
  s_sharedCount--;
  [s_sharedMetalCommandQueue release];
  if (s_sharedCount == 0) {
    s_sharedMetalCommandQueue = nil;
  }
}
 
GHOST_TSuccess GHOST_ContextCGL::swapBuffers()
{
  if (m_metalView) {
    metalSwapBuffers();
  }
  return GHOST_kSuccess;
}
 
GHOST_TSuccess GHOST_ContextCGL::setSwapInterval(int interval)
{
  mtl_SwapInterval = interval;
  return GHOST_kSuccess;
}
 
GHOST_TSuccess GHOST_ContextCGL::getSwapInterval(int &intervalOut)
{
  intervalOut = mtl_SwapInterval;
  return GHOST_kSuccess;
}
 
GHOST_TSuccess GHOST_ContextCGL::activateDrawingContext()
{
  active_context_ = this;
  return GHOST_kSuccess;
}
 
GHOST_TSuccess GHOST_ContextCGL::releaseDrawingContext()
{
  active_context_ = nullptr;
  return GHOST_kSuccess;
}
 
unsigned int GHOST_ContextCGL::getDefaultFramebuffer()
{
  /* NOTE(Metal): This is not valid. */
  return 0;
}
 
GHOST_TSuccess GHOST_ContextCGL::updateDrawingContext()
{
  if (m_metalView) {
    metalUpdateFramebuffer();
    return GHOST_kSuccess;
  }
  return GHOST_kFailure;
}
 
id<MTLTexture> GHOST_ContextCGL::metalOverlayTexture()
{
  /* Increment Swap-chain - Only needed if context is requesting a new texture */
  current_swapchain_index = (current_swapchain_index + 1) % METAL_SWAPCHAIN_SIZE;
 
  /* Ensure backing texture is ready for current swapchain index */
  updateDrawingContext();
 
  /* Return texture. */
  return m_defaultFramebufferMetalTexture[current_swapchain_index].texture;
}
 
MTLCommandQueue *GHOST_ContextCGL::metalCommandQueue()
{
  return s_sharedMetalCommandQueue;
}
MTLDevice *GHOST_ContextCGL::metalDevice()
{
  id<MTLDevice> device = m_metalLayer.device;
  return (MTLDevice *)device;
}
 
void GHOST_ContextCGL::metalRegisterPresentCallback(void (*callback)(
    MTLRenderPassDescriptor *, id<MTLRenderPipelineState>, id<MTLTexture>, id<CAMetalDrawable>))
{
  this->contextPresentCallback = callback;
}
 
GHOST_TSuccess GHOST_ContextCGL::initializeDrawingContext()
{
  @autoreleasepool {
    if (m_metalView) {
      metalInitFramebuffer();
    }
  }
  active_context_ = this;
  return GHOST_kSuccess;
}
 
GHOST_TSuccess GHOST_ContextCGL::releaseNativeHandles()
{
  m_metalView = nil;
 
  return GHOST_kSuccess;
}
 
void GHOST_ContextCGL::metalInit()
{
  @autoreleasepool {
    id<MTLDevice> device = m_metalLayer.device;
 
    /* Create a command queue for blit/present operation.
     * NOTE: All context should share a single command queue
     * to ensure correct ordering of work submitted from multiple contexts. */
    if (s_sharedMetalCommandQueue == nil) {
      s_sharedMetalCommandQueue = (MTLCommandQueue *)[device
          newCommandQueueWithMaxCommandBufferCount:GHOST_ContextCGL::max_command_buffer_count];
    }
    /* Ensure active GHOSTContext retains a reference to the shared context. */
    [s_sharedMetalCommandQueue retain];
    s_sharedCount++;
 
    /* Create shaders for blit operation. */
    NSString *source = @R"msl(
      using namespace metal;
 
      struct Vertex {
        float4 position [[position]];
        float2 texCoord [[attribute(0)]];
      };
 
      vertex Vertex vertex_shader(uint v_id [[vertex_id]]) {
        Vertex vtx;
 
        vtx.position.x = float(v_id & 1) * 4.0 - 1.0;
        vtx.position.y = float(v_id >> 1) * 4.0 - 1.0;
        vtx.position.z = 0.0;
        vtx.position.w = 1.0;
 
        vtx.texCoord = vtx.position.xy * 0.5 + 0.5;
 
        return vtx;
      }
 
      constexpr sampler s {};
 
      fragment float4 fragment_shader(Vertex v [[stage_in]],
                      texture2d<float> t [[texture(0)]]) {
 
        /* Final blit should ensure alpha is 1.0. This resolves
         * rendering artifacts for blitting of final back-buffer. */
        float4 out_tex = t.sample(s, v.texCoord);
        out_tex.a = 1.0;
        return out_tex;
      }
    )msl";
 
    MTLCompileOptions *options = [[[MTLCompileOptions alloc] init] autorelease];
    options.languageVersion = MTLLanguageVersion1_1;
 
    NSError *error = nil;
    id<MTLLibrary> library = [device newLibraryWithSource:source options:options error:&error];
    if (error) {
      ghost_fatal_error_dialog(
          "GHOST_ContextCGL::metalInit: newLibraryWithSource:options:error: failed!");
    }
 
    /* Create a render pipeline for blit operation. */
    MTLRenderPipelineDescriptor *desc = [[[MTLRenderPipelineDescriptor alloc] init] autorelease];
 
    desc.fragmentFunction = [library newFunctionWithName:@"fragment_shader"];
    desc.vertexFunction = [library newFunctionWithName:@"vertex_shader"];
    [desc.colorAttachments objectAtIndexedSubscript:0].pixelFormat =
        METAL_FRAMEBUFFERPIXEL_FORMAT_EDR;
 
    /* Ensure library is released. */
    [library autorelease];
 
    m_metalRenderPipeline = (MTLRenderPipelineState *)[device
        newRenderPipelineStateWithDescriptor:desc
                                       error:&error];
    if (error) {
      ghost_fatal_error_dialog(
          "GHOST_ContextCGL::metalInit: newRenderPipelineStateWithDescriptor:error: failed!");
    }
 
    /* Create a render pipeline to composite things rendered with Metal on top
     * of the frame-buffer contents. Uses the same vertex and fragment shader
     * as the blit above, but with alpha blending enabled. */
    desc.label = @"Metal Overlay";
    desc.colorAttachments[0].blendingEnabled = YES;
    desc.colorAttachments[0].sourceRGBBlendFactor = MTLBlendFactorSourceAlpha;
    desc.colorAttachments[0].destinationRGBBlendFactor = MTLBlendFactorOneMinusSourceAlpha;
 
    if (error) {
      ghost_fatal_error_dialog(
          "GHOST_ContextCGL::metalInit: newRenderPipelineStateWithDescriptor:error: failed (when "
          "creating the Metal overlay pipeline)!");
    }
 
    [desc.fragmentFunction release];
    [desc.vertexFunction release];
  }
}
 
void GHOST_ContextCGL::metalFree()
{
  if (m_metalRenderPipeline) {
    [m_metalRenderPipeline release];
    m_metalRenderPipeline = nil;
  }
 
  for (int i = 0; i < METAL_SWAPCHAIN_SIZE; i++) {
    if (m_defaultFramebufferMetalTexture[i].texture) {
      [m_defaultFramebufferMetalTexture[i].texture release];
      m_defaultFramebufferMetalTexture[i].texture = nil;
    }
  }
}
 
void GHOST_ContextCGL::metalInitFramebuffer()
{
  updateDrawingContext();
}
 
void GHOST_ContextCGL::metalUpdateFramebuffer()
{
  @autoreleasepool {
    const NSRect bounds = [m_metalView bounds];
    const NSSize backingSize = [m_metalView convertSizeToBacking:bounds.size];
    const size_t width = size_t(backingSize.width);
    const size_t height = size_t(backingSize.height);
 
    if (m_defaultFramebufferMetalTexture[current_swapchain_index].texture &&
        m_defaultFramebufferMetalTexture[current_swapchain_index].texture.width == width &&
        m_defaultFramebufferMetalTexture[current_swapchain_index].texture.height == height)
    {
      return;
    }
 
    /* Free old texture */
    [m_defaultFramebufferMetalTexture[current_swapchain_index].texture release];
 
    id<MTLDevice> device = m_metalLayer.device;
    MTLTextureDescriptor *overlayDesc = [MTLTextureDescriptor
        texture2DDescriptorWithPixelFormat:METAL_FRAMEBUFFERPIXEL_FORMAT_EDR
                                     width:width
                                    height:height
                                 mipmapped:NO];
    overlayDesc.storageMode = MTLStorageModePrivate;
    overlayDesc.usage = MTLTextureUsageRenderTarget | MTLTextureUsageShaderRead;
 
    id<MTLTexture> overlayTex = [device newTextureWithDescriptor:overlayDesc];
    if (!overlayTex) {
      ghost_fatal_error_dialog(
          "GHOST_ContextCGL::metalUpdateFramebuffer: failed to create Metal overlay texture!");
    }
    else {
      overlayTex.label = [NSString
          stringWithFormat:@"Metal Overlay for GHOST Context %p", this];  //@"";
    }
 
    m_defaultFramebufferMetalTexture[current_swapchain_index].texture = overlayTex;
 
    /* Clear texture on create */
    id<MTLCommandBuffer> cmdBuffer = [s_sharedMetalCommandQueue commandBuffer];
    MTLRenderPassDescriptor *passDescriptor = [MTLRenderPassDescriptor renderPassDescriptor];
    {
      auto attachment = [passDescriptor.colorAttachments objectAtIndexedSubscript:0];
      attachment.texture = m_defaultFramebufferMetalTexture[current_swapchain_index].texture;
      attachment.loadAction = MTLLoadActionClear;
      attachment.clearColor = MTLClearColorMake(0.294, 0.294, 0.294, 1.000);
      attachment.storeAction = MTLStoreActionStore;
    }
    {
      id<MTLRenderCommandEncoder> enc = [cmdBuffer
          renderCommandEncoderWithDescriptor:passDescriptor];
      [enc endEncoding];
    }
    [cmdBuffer commit];
 
    m_metalLayer.drawableSize = CGSizeMake(CGFloat(width), CGFloat(height));
  }
}
 
void GHOST_ContextCGL::metalSwapBuffers()
{
  @autoreleasepool {
    updateDrawingContext();
 
    id<CAMetalDrawable> drawable = [m_metalLayer nextDrawable];
    if (!drawable) {
      return;
    }
 
    MTLRenderPassDescriptor *passDescriptor = [MTLRenderPassDescriptor renderPassDescriptor];
    {
      auto attachment = [passDescriptor.colorAttachments objectAtIndexedSubscript:0];
      attachment.texture = drawable.texture;
      attachment.loadAction = MTLLoadActionClear;
      attachment.clearColor = MTLClearColorMake(1.0, 0.294, 0.294, 1.000);
      attachment.storeAction = MTLStoreActionStore;
    }
 
    assert(contextPresentCallback);
    assert(m_defaultFramebufferMetalTexture[current_swapchain_index].texture != nil);
    (*contextPresentCallback)(passDescriptor,
                              (id<MTLRenderPipelineState>)m_metalRenderPipeline,
                              m_defaultFramebufferMetalTexture[current_swapchain_index].texture,
                              drawable);
  }
}