Initial shot at a renderer target for Apple's Metal API.

This isn't complete, but is enough to run testsprite2. It's currently
Mac-only; with a little work to figure out how to properly glue in a Metal
layer to a UIView, this will likely work on iOS, too.

This is only wired up to the configure script right now, and disabled by
default. CMake and Xcode still need their bits filled in as appropriate.

configure.in

@@ -2053,6 +2053,19 @@ AC_HELP_STRING([--enable-video-cocoa], [use Cocoa video driver [[default=yes]]])
     fi
 }
 
+CheckMETAL()
+{
+    AC_ARG_ENABLE(render-metal,
+AC_HELP_STRING([--enable-render-metal], [enable the Metal render driver [[default=no]]]),
+                                , enable_render_metal=no)
+    if test x$enable_render = xyes -a x$enable_render_metal = xyes; then
+        dnl This should maybe make sure you have a supported SDK version.
+        AC_DEFINE(SDL_VIDEO_RENDER_METAL, 1, [ ])
+        SOURCES="$SOURCES $srcdir/src/render/metal/*.m"
+    fi
+}
+
+
 dnl Find DirectFB
 CheckDirectFB()
 {
@@ -2103,7 +2116,6 @@ AC_HELP_STRING([--enable-directfb-shared], [dynamically load directfb support [[
                               , enable_directfb_shared=yes)
 
             AC_DEFINE(SDL_VIDEO_DRIVER_DIRECTFB, 1, [ ])
-            AC_DEFINE(SDL_VIDEO_RENDER_DIRECTFB, 1, [ ])
             SOURCES="$SOURCES $srcdir/src/video/directfb/*.c"
             EXTRA_CFLAGS="$EXTRA_CFLAGS $DIRECTFB_CFLAGS"
 
@@ -3636,8 +3648,9 @@ AC_HELP_STRING([--enable-render-d3d], [enable the Direct3D render driver [[defau
         CheckDiskAudio
         CheckDummyAudio
         CheckDLOPEN
-        CheckPTHREAD
+        CheckMETAL
         CheckVulkan
+        CheckPTHREAD
 
         # Set up files for the audio library
         if test x$enable_audio = xyes; then
@@ -3701,6 +3714,10 @@ AC_HELP_STRING([--enable-render-d3d], [enable the Direct3D render driver [[defau
         EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,-framework,OpenGLES"
         EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,-framework,QuartzCore"
         EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,-framework,UIKit"
+
+        if test x$enable_render = xyes -a x$enable_render_metal = xyes; then
+            EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,-framework,Metal"
+        fi
         ;;
     *-*-darwin* )
         # This could be either full "Mac OS X", or plain "Darwin" which is
@@ -3719,6 +3736,7 @@ AC_HELP_STRING([--enable-render-d3d], [enable the Direct3D render driver [[defau
         CheckDummyAudio
         CheckDLOPEN
         CheckCOCOA
+        CheckMETAL
         CheckX11
         CheckMacGL
         CheckOpenGLX11

include/SDL_config.h.cmake

@@ -356,6 +356,7 @@
 #cmakedefine SDL_VIDEO_RENDER_OGL_ES @SDL_VIDEO_RENDER_OGL_ES@
 #cmakedefine SDL_VIDEO_RENDER_OGL_ES2 @SDL_VIDEO_RENDER_OGL_ES2@
 #cmakedefine SDL_VIDEO_RENDER_DIRECTFB @SDL_VIDEO_RENDER_DIRECTFB@
+#cmakedefine SDL_VIDEO_RENDER_METAL @SDL_VIDEO_RENDER_METAL@
 
 /* Enable OpenGL support */
 #cmakedefine SDL_VIDEO_OPENGL @SDL_VIDEO_OPENGL@

include/SDL_config.h.in

@@ -354,6 +354,7 @@
 #undef SDL_VIDEO_RENDER_OGL_ES
 #undef SDL_VIDEO_RENDER_OGL_ES2
 #undef SDL_VIDEO_RENDER_DIRECTFB
+#undef SDL_VIDEO_RENDER_METAL
 
 /* Enable OpenGL support */
 #undef SDL_VIDEO_OPENGL

include/SDL_config_macosx.h

@@ -183,6 +183,10 @@
 #define SDL_VIDEO_RENDER_OGL_ES2 1
 #endif
 
+#ifndef SDL_VIDEO_RENDER_METAL
+#define SDL_VIDEO_RENDER_METAL    1
+#endif
+
 /* Enable OpenGL support */
 #ifndef SDL_VIDEO_OPENGL
 #define SDL_VIDEO_OPENGL    1

src/render/SDL_render.c

@@ -92,6 +92,9 @@ static const SDL_RenderDriver *render_drivers[] = {
 #if SDL_VIDEO_RENDER_DIRECTFB
     &DirectFB_RenderDriver,
 #endif
+#if SDL_VIDEO_RENDER_METAL
+    &METAL_RenderDriver,
+#endif
 #if SDL_VIDEO_RENDER_PSP
     &PSP_RenderDriver,
 #endif

src/render/SDL_sysrender.h

@@ -184,6 +184,7 @@ extern SDL_RenderDriver GL_RenderDriver;
 extern SDL_RenderDriver GLES2_RenderDriver;
 extern SDL_RenderDriver GLES_RenderDriver;
 extern SDL_RenderDriver DirectFB_RenderDriver;
+extern SDL_RenderDriver METAL_RenderDriver;
 extern SDL_RenderDriver PSP_RenderDriver;
 extern SDL_RenderDriver SW_RenderDriver;
 

src/render/metal/SDL_shaders_metal.metal

@@ -0,0 +1,34 @@
+#include <metal_texture>
+
+using namespace metal;
+
+vertex float4 SDL_Simple_vertex(constant float2 *position [[buffer(0)]], uint vid [[vertex_id]])
+{
+    return float4(position[vid].x, position[vid].y, 0.0f, 1.0f);
+}
+ 
+fragment float4 SDL_Simple_fragment(constant float4 &col [[buffer(0)]])
+{
+    return col;
+}
+
+struct CopyVertex
+{
+    float4 position [[position]];
+    float2 texcoord;
+};
+
+vertex CopyVertex SDL_Copy_vertex(constant float2 *position [[buffer(0)]], constant float2 *texcoords [[buffer(1)]], uint vid [[vertex_id]])
+{
+    CopyVertex retval;
+    retval.position = float4(position[vid].x, position[vid].y, 0.0f, 1.0f);
+    retval.texcoord = texcoords[vid];
+    return retval;
+}
+
+fragment float4 SDL_Copy_fragment(CopyVertex vert [[stage_in]], constant float4 &col [[buffer(0)]], texture2d<float> tex [[texture(0)]])
+{
+    constexpr sampler samp; // !!! FIXME: linear sampling, etc?
+    return tex.sample(samp, vert.texcoord) * col;
+}
+

src/render/metal/build-metal-shaders.sh

@@ -0,0 +1,13 @@
+#!/bin/bash
+
+set -x
+set -e
+
+cd `dirname "$0"`
+rm -f sdl.air sdl.metalar sdl.metallib
+/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/usr/bin/metal -std=osx-metal1.1 -Wall -O3 -o ./sdl.air ./SDL_shaders_metal.metal
+/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/usr/bin/metal-ar rc sdl.metalar sdl.air
+/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/usr/bin/metallib -o sdl.metallib sdl.metalar
+xxd -i sdl.metallib |perl -w -p -e 's/\Aunsigned /const unsigned /;' >./SDL_shaders_metal.c
+rm -f sdl.air sdl.metalar sdl.metallib
+