Add GLFW_CONTEXT_RENDERER

This window hint allows choosing between hardware and software renderers (where available) for the created OpenGL or OpenGL ES context. Fixes glfw#589.
HinTak · Jun 4, 2024 · 46ff90e · 46ff90e
1 parent 37e0098
commit 46ff90e
Show file tree

Hide file tree

Showing 10 changed files with 94 additions and 11 deletions.
diff --git a/README.md b/README.md
@@ -132,6 +132,8 @@ information on what to include when reporting a bug.
  - [Null] Added EGL context creation on Mesa via `EGL_MESA_platform_surfaceless`
  - [EGL] Allowed native access on Wayland with `GLFW_CONTEXT_CREATION_API` set to
    `GLFW_NATIVE_CONTEXT_API` (#2518)
+ - Added `GLFW_CONTEXT_RENDERER` window hint and `GLFW_HARDWARE_RENDERER` and
+   `GLFW_SOFTWARE_RENDERER` hint values (#589)
 
 
 ## Contact

diff --git a/docs/window.md b/docs/window.md
@@ -375,6 +375,11 @@ does not update the window contents when its buffers are swapped.  Use OpenGL
 functions or the OSMesa native access functions @ref glfwGetOSMesaColorBuffer
 and @ref glfwGetOSMesaDepthBuffer to retrieve the framebuffer contents.
 
+@anchor GLFW_CONTEXT_RENDERER_hint
+__GLFW_CONTEXT_RENDERER__ specifies whether to create the context using
+a hardware or software renderer, if that is possible to control on the current
+platform.
+
 @anchor GLFW_CONTEXT_VERSION_MAJOR_hint
 @anchor GLFW_CONTEXT_VERSION_MINOR_hint
 __GLFW_CONTEXT_VERSION_MAJOR__ and __GLFW_CONTEXT_VERSION_MINOR__ specify the
@@ -566,6 +571,7 @@ GLFW_SRGB_CAPABLE             | `GLFW_FALSE`                | `GLFW_TRUE` or `GL
 GLFW_DOUBLEBUFFER             | `GLFW_TRUE`                 | `GLFW_TRUE` or `GLFW_FALSE`
 GLFW_CLIENT_API               | `GLFW_OPENGL_API`           | `GLFW_OPENGL_API`, `GLFW_OPENGL_ES_API` or `GLFW_NO_API`
 GLFW_CONTEXT_CREATION_API     | `GLFW_NATIVE_CONTEXT_API`   | `GLFW_NATIVE_CONTEXT_API`, `GLFW_EGL_CONTEXT_API` or `GLFW_OSMESA_CONTEXT_API`
+GLFW_CONTEXT_RENDERER         | `GLFW_HARDWARE_RENDERER`    | `GLFW_HARDWARE_RENDERER` or `GLFW_SOFTWARE_RENDERER`
 GLFW_CONTEXT_VERSION_MAJOR    | 1                           | Any valid major version number of the chosen client API
 GLFW_CONTEXT_VERSION_MINOR    | 0                           | Any valid minor version number of the chosen client API
 GLFW_CONTEXT_ROBUSTNESS       | `GLFW_NO_ROBUSTNESS`        | `GLFW_NO_ROBUSTNESS`, `GLFW_NO_RESET_NOTIFICATION` or `GLFW_LOSE_CONTEXT_ON_RESET`

diff --git a/include/GLFW/glfw3.h b/include/GLFW/glfw3.h
@@ -1108,6 +1108,8 @@ extern "C" {
  *  [GLFW_SCALE_FRAMEBUFFER](@ref GLFW_SCALE_FRAMEBUFFER_hint) window hint for
  *  compatibility with earlier versions.
  */
+#define GLFW_CONTEXT_RENDERER       0x0002200E
+
 #define GLFW_COCOA_RETINA_FRAMEBUFFER 0x00023001
 /*! @brief macOS specific
  *  [window hint](@ref GLFW_COCOA_FRAME_NAME_hint).
@@ -1180,6 +1182,9 @@ extern "C" {
 #define GLFW_WAYLAND_PREFER_LIBDECOR    0x00038001
 #define GLFW_WAYLAND_DISABLE_LIBDECOR   0x00038002
 
+#define GLFW_HARDWARE_RENDERER      0x00039001
+#define GLFW_SOFTWARE_RENDERER      0x00039002
+
 #define GLFW_ANY_POSITION           0x80000000
 
 /*! @defgroup shapes Standard cursor shapes

diff --git a/src/context.c b/src/context.c
@@ -56,6 +56,15 @@ GLFWbool _glfwIsValidContextConfig(const _GLFWctxconfig* ctxconfig)
         return GLFW_FALSE;
     }
 
+    if (ctxconfig->renderer != GLFW_HARDWARE_RENDERER &&
+        ctxconfig->renderer != GLFW_SOFTWARE_RENDERER)
+    {
+        _glfwInputError(GLFW_INVALID_ENUM,
+                        "Invalid context renderer 0x%08X",
+                        ctxconfig->renderer);
+        return GLFW_FALSE;
+    }
+
     if (ctxconfig->client != GLFW_NO_API &&
         ctxconfig->client != GLFW_OPENGL_API &&
         ctxconfig->client != GLFW_OPENGL_ES_API)

diff --git a/src/glx_context.c b/src/glx_context.c
@@ -467,6 +467,9 @@ GLFWbool _glfwCreateContextGLX(_GLFWwindow* window,
         return GLFW_FALSE;
     }
 
+    if (ctxconfig->renderer == GLFW_SOFTWARE_RENDERER)
+        setenv("LIBGL_ALWAYS_SOFTWARE", "1", 1);
+
     if (ctxconfig->client == GLFW_OPENGL_ES_API)
     {
         if (!_glfw.glx.ARB_create_context ||

diff --git a/src/internal.h b/src/internal.h
@@ -449,6 +449,7 @@ struct _GLFWctxconfig
     int           profile;
     int           robustness;
     int           release;
+    int           renderer;
     _GLFWwindow*  share;
     struct {
         GLFWbool  offline;

diff --git a/src/nsgl_context.m b/src/nsgl_context.m
@@ -31,6 +31,8 @@
 #include <unistd.h>
 #include <math.h>
 #include <assert.h>
+#include <OpenGL/CGLRenderers.h>
+
 
 static void makeContextCurrentNSGL(_GLFWwindow* window)
 {
@@ -225,9 +227,17 @@ GLFWbool _glfwCreateContextNSGL(_GLFWwindow* window,
     NSOpenGLPixelFormatAttribute attribs[40];
     int index = 0;
 
-    ADD_ATTRIB(NSOpenGLPFAAccelerated);
     ADD_ATTRIB(NSOpenGLPFAClosestPolicy);
 
+    if (ctxconfig->renderer == GLFW_HARDWARE_RENDERER)
+    {
+        ADD_ATTRIB(NSOpenGLPFAAccelerated);
+    }
+    else if (ctxconfig->renderer == GLFW_SOFTWARE_RENDERER)
+    {
+        SET_ATTRIB(NSOpenGLPFARendererID, kCGLRendererGenericFloatID);
+    }
+
     if (ctxconfig->nsgl.offline)
     {
         ADD_ATTRIB(NSOpenGLPFAAllowOfflineRenderers);

diff --git a/src/wgl_context.c b/src/wgl_context.c
@@ -166,8 +166,22 @@ static int choosePixelFormatWGL(_GLFWwindow* window,
             if (FIND_ATTRIB_VALUE(WGL_PIXEL_TYPE_ARB) != WGL_TYPE_RGBA_ARB)
                 continue;
 
-            if (FIND_ATTRIB_VALUE(WGL_ACCELERATION_ARB) == WGL_NO_ACCELERATION_ARB)
-                continue;
+            if (ctxconfig->renderer == GLFW_HARDWARE_RENDERER)
+            {
+                if (FIND_ATTRIB_VALUE(WGL_ACCELERATION_ARB) ==
+                    WGL_NO_ACCELERATION_ARB)
+                {
+                    continue;
+                }
+            }
+            else if (ctxconfig->renderer == GLFW_SOFTWARE_RENDERER)
+            {
+                if (FIND_ATTRIB_VALUE(WGL_ACCELERATION_ARB) !=
+                    WGL_NO_ACCELERATION_ARB)
+                {
+                    continue;
+                }
+            }
 
             if (FIND_ATTRIB_VALUE(WGL_DOUBLE_BUFFER_ARB) != fbconfig->doublebuffer)
                 continue;
@@ -235,10 +249,21 @@ static int choosePixelFormatWGL(_GLFWwindow* window,
                 continue;
             }
 
-            if (!(pfd.dwFlags & PFD_GENERIC_ACCELERATED) &&
-                (pfd.dwFlags & PFD_GENERIC_FORMAT))
+            if (ctxconfig->renderer == GLFW_HARDWARE_RENDERER)
             {
-                continue;
+                if (!(pfd.dwFlags & PFD_GENERIC_ACCELERATED) &&
+                    (pfd.dwFlags & PFD_GENERIC_FORMAT))
+                {
+                    continue;
+                }
+            }
+            else if (ctxconfig->renderer == GLFW_SOFTWARE_RENDERER)
+            {
+                if ((pfd.dwFlags & PFD_GENERIC_ACCELERATED) &&
+                    !(pfd.dwFlags & PFD_GENERIC_FORMAT))
+                {
+                    continue;
+                }
             }
 
             if (pfd.iPixelType != PFD_TYPE_RGBA)

diff --git a/src/window.c b/src/window.c
@@ -259,10 +259,11 @@ void glfwDefaultWindowHints(void)
 
     // The default is OpenGL with minimum version 1.0
     memset(&_glfw.hints.context, 0, sizeof(_glfw.hints.context));
-    _glfw.hints.context.client = GLFW_OPENGL_API;
-    _glfw.hints.context.source = GLFW_NATIVE_CONTEXT_API;
-    _glfw.hints.context.major  = 1;
-    _glfw.hints.context.minor  = 0;
+    _glfw.hints.context.client   = GLFW_OPENGL_API;
+    _glfw.hints.context.source   = GLFW_NATIVE_CONTEXT_API;
+    _glfw.hints.context.renderer = GLFW_HARDWARE_RENDERER;
+    _glfw.hints.context.major    = 1;
+    _glfw.hints.context.minor    = 0;
 
     // The default is a focused, visible, resizable window with decorations
     memset(&_glfw.hints.window, 0, sizeof(_glfw.hints.window));
@@ -404,6 +405,9 @@ GLFWAPI void glfwWindowHint(int hint, int value)
         case GLFW_CONTEXT_CREATION_API:
             _glfw.hints.context.source = value;
             return;
+        case GLFW_CONTEXT_RENDERER:
+            _glfw.hints.context.renderer = value;
+            return;
         case GLFW_CONTEXT_VERSION_MAJOR:
             _glfw.hints.context.major = value;
             return;

diff --git a/tests/glfwinfo.c b/tests/glfwinfo.c
@@ -71,6 +71,9 @@
 #define PLATFORM_NAME_X11   "x11"
 #define PLATFORM_NAME_NULL  "null"
 
+#define RENDERER_NAME_HW    "hw"
+#define RENDERER_NAME_SW    "sw"
+
 static void usage(void)
 {
     printf("Usage: glfwinfo [OPTION]...\n");
@@ -92,6 +95,9 @@ static void usage(void)
                                         API_NAME_NATIVE " or "
                                         API_NAME_EGL " or "
                                         API_NAME_OSMESA ")\n");
+    printf("      --renderer=RENDERER   the renderer to use ("
+                                        RENDERER_NAME_HW " or "
+                                        RENDERER_NAME_SW ")\n");
     printf("  -d, --debug               request a debug context\n");
     printf("  -f, --forward             require a forward-compatible context\n");
     printf("  -h, --help                show this help\n");
@@ -384,7 +390,7 @@ int main(int argc, char** argv)
     bool cocoa_graphics_switching = false;
     bool disable_xcb_surface = false;
 
-    enum { PLATFORM, CLIENT, CONTEXT, BEHAVIOR, DEBUG_CONTEXT, FORWARD, HELP,
+    enum { PLATFORM, CLIENT, CONTEXT, RENDERER, BEHAVIOR, DEBUG_CONTEXT, FORWARD, HELP,
            EXTENSIONS, LAYERS,
            MAJOR, MINOR, PROFILE, ROBUSTNESS, VERSION,
            REDBITS, GREENBITS, BLUEBITS, ALPHABITS, DEPTHBITS, STENCILBITS,
@@ -397,6 +403,7 @@ int main(int argc, char** argv)
         { "behavior",           1, NULL, BEHAVIOR },
         { "client-api",         1, NULL, CLIENT },
         { "context-api",        1, NULL, CONTEXT },
+        { "renderer",           1, NULL, RENDERER },
         { "debug",              0, NULL, DEBUG_CONTEXT },
         { "forward",            0, NULL, FORWARD },
         { "help",               0, NULL, HELP },
@@ -490,6 +497,17 @@ int main(int argc, char** argv)
                     exit(EXIT_FAILURE);
                 }
                 break;
+            case RENDERER:
+                if (strcasecmp(optarg, RENDERER_NAME_HW) == 0)
+                    glfwWindowHint(GLFW_CONTEXT_RENDERER, GLFW_HARDWARE_RENDERER);
+                else if (strcasecmp(optarg, RENDERER_NAME_SW) == 0)
+                    glfwWindowHint(GLFW_CONTEXT_RENDERER, GLFW_SOFTWARE_RENDERER);
+                else
+                {
+                    usage();
+                    exit(EXIT_FAILURE);
+                }
+                break;
             case 'd':
             case DEBUG_CONTEXT:
                 context_debug = true;