Fix pandagl dependency

Author: bluekyu

cmake/Findpanda3d.cmake

@@ -62,7 +62,11 @@ function(_panda3d_get_dependencies component_name ret)
     set(panda3d_DEPENDENCIES_pandadx9           p3windisplay)
     set(panda3d_DEPENDENCIES_p3framework        panda)
     set(panda3d_DEPENDENCIES_pandaegg           panda)
-    set(panda3d_DEPENDENCIES_pandagl            pandafx p3windisplay)
+    if(WIN32)
+        set(panda3d_DEPENDENCIES_pandagl            p3windisplay)
+    else()
+        set(panda3d_DEPENDENCIES_pandagl            panda)
+    endif()
     set(panda3d_DEPENDENCIES_pandagles          panda)
     set(panda3d_DEPENDENCIES_pandagles2         panda)
     set(panda3d_DEPENDENCIES_pandaode           panda)

docs/framework/panda3d_pipeline.md

@@ -113,3 +113,16 @@ PandaFramework::task_igloop()
     }
 }
 ```
+
+#### GraphicsOutput
+```cpp
+GraphicsOutput::begin_frame()
+{
+    ...     // GL make current
+
+    GraphicsStateGuardian::begin_frame()
+    {
+        PreparedGraphicsObjects::begin_frame();
+    }
+}
+```