display: Make context current before dispatching compute shader

panda/src/cocoagldisplay/cocoaGLGraphicsStateGuardian.h

@@ -39,6 +39,8 @@ public:
 
   virtual ~CocoaGLGraphicsStateGuardian();
 
+  virtual bool make_current();
+
   INLINE void lock_context();
   INLINE void unlock_context();
 

panda/src/cocoagldisplay/cocoaGLGraphicsStateGuardian.mm

@@ -297,6 +297,18 @@ choose_pixel_format(const FrameBufferProperties &properties,
   }
 }
 
+/**
+ * Ensures that the context is current.  May return false if the context cannot
+ * be bound without a window.
+ */
+bool CocoaGLGraphicsStateGuardian::
+make_current() {
+  lock_context();
+  [_context makeCurrentContext];
+  unlock_context();
+  return true;
+}
+
 /**
  * Queries the runtime version of OpenGL in use.
  */

panda/src/display/graphicsEngine.cxx

@@ -1206,6 +1206,7 @@ dispatch_compute(const LVecBase3i &work_groups, const RenderState *state, Graphi
   nassertv(gsg != nullptr);
 
   run_on_draw_thread([=] () {
+    gsg->make_current();
     gsg->push_group_marker(std::string("Compute ") + shader->get_filename(Shader::ST_compute).get_basename());
     gsg->set_state_and_transform(state, TransformState::make_identity());
     gsg->dispatch_compute(work_groups[0], work_groups[1], work_groups[2]);

panda/src/display/graphicsStateGuardian.cxx

@@ -3084,6 +3084,15 @@ reset() {
   _is_valid = true;
 }
 
+/**
+ * Ensures that the context is current.  May return false if the context cannot
+ * be bound without a window.
+ */
+bool GraphicsStateGuardian::
+make_current() {
+  return false;
+}
+
 /**
  * Simultaneously resets the render state and the transform state.
  *

panda/src/display/graphicsStateGuardian.h

@@ -421,6 +421,7 @@ public:
   INLINE bool reset_if_new();
   INLINE void mark_new();
   virtual void reset();
+  virtual bool make_current();
 
   INLINE CPT(TransformState) get_external_transform() const;
   INLINE CPT(TransformState) get_internal_transform() const;

panda/src/egldisplay/eglGraphicsStateGuardian.cxx

@@ -280,12 +280,36 @@ void eglGraphicsStateGuardian::
 reset() {
   BaseGraphicsStateGuardian::reset();
 
+#ifdef OPENGLES
+  _supports_surfaceless = has_extension("GL_OES_surfaceless_context") &&
+#else
+  _supports_surfaceless =
+#endif
+    has_extension("EGL_KHR_surfaceless_context");
+
   if (_gl_renderer == "Software Rasterizer") {
     _fbprops.set_force_software(1);
     _fbprops.set_force_hardware(0);
   }
 }
 
+/**
+ * Ensures that the context is current.  May return false if the context cannot
+ * be bound without a window.
+ */
+bool eglGraphicsStateGuardian::
+make_current() {
+  if (eglGetCurrentContext() == _context) {
+    return true;
+  }
+
+  if (_supports_surfaceless) {
+    return eglMakeCurrent(_egl_display, EGL_NO_SURFACE, EGL_NO_SURFACE, _context) != EGL_FALSE;
+  }
+
+  return false;
+}
+
 /**
  * Returns true if the runtime GLX version number is at least the indicated
  * value, false otherwise.

panda/src/egldisplay/eglGraphicsStateGuardian.h

@@ -49,6 +49,7 @@ public:
   virtual ~eglGraphicsStateGuardian();
 
   virtual void reset();
+  virtual bool make_current();
 
   bool egl_is_at_least_version(int major_version, int minor_version) const;
 
@@ -60,6 +61,7 @@ public:
 #endif
   EGLConfig _fbconfig;
   FrameBufferProperties _fbprops;
+  bool _supports_surfaceless = false;
 
 protected:
   virtual void gl_flush() const;

panda/src/glxdisplay/glxGraphicsStateGuardian.cxx

@@ -434,6 +434,19 @@ choose_pixel_format(const FrameBufferProperties &properties,
   _context_has_pbuffer = false;
 }
 
+/**
+ * Ensures that the context is current.  May return false if the context cannot
+ * be bound without a window.
+ */
+bool glxGraphicsStateGuardian::
+make_current() {
+  if (glXGetCurrentContext() == _context) {
+    return true;
+  }
+
+  return false;
+}
+
 /**
  * Returns true if the runtime GLX version number is at least the indicated
  * value, false otherwise.

panda/src/glxdisplay/glxGraphicsStateGuardian.h

@@ -88,6 +88,8 @@ public:
 
   virtual ~glxGraphicsStateGuardian();
 
+  virtual bool make_current();
+
   bool glx_is_at_least_version(int major_version, int minor_version) const;
 
   GLXContext _share_context;