From bac5401a9d2bb5977f7f8cfedb6dfdc187ef5255 Mon Sep 17 00:00:00 2001
From: rdb <git@rdb.name>
Date: Wed, 28 Oct 2015 13:18:12 +0100
Subject: [PATCH] Add GL function pointers for indirect draw

---
 panda/src/display/graphicsStateGuardian.I      | 12 ++++++++++++
 panda/src/display/graphicsStateGuardian.cxx    |  1 +
 panda/src/display/graphicsStateGuardian.h      |  2 ++
 .../glstuff/glGraphicsStateGuardian_src.cxx    | 18 ++++++++++++++++++
 .../src/glstuff/glGraphicsStateGuardian_src.h  |  5 +++++
 5 files changed, 38 insertions(+)

diff --git a/panda/src/display/graphicsStateGuardian.I b/panda/src/display/graphicsStateGuardian.I
index 1646f4a741..8a3a5b6f5b 100644
--- a/panda/src/display/graphicsStateGuardian.I
+++ b/panda/src/display/graphicsStateGuardian.I
@@ -808,6 +808,18 @@ get_supports_geometry_instancing() const {
   return _supports_geometry_instancing;
 }
 
+////////////////////////////////////////////////////////////////////
+//     Function: GraphicsStateGuardian::get_supports_indirect_draw
+//       Access: Published
+//  Description: Returns true if this particular GSG supports
+//               draw calls for which the information comes from a
+//               buffer.
+////////////////////////////////////////////////////////////////////
+INLINE bool GraphicsStateGuardian::
+get_supports_indirect_draw() const {
+  return _supports_indirect_draw;
+}
+
 ////////////////////////////////////////////////////////////////////
 //     Function: GraphicsStateGuardian::get_supports_occlusion_query
 //       Access: Published
diff --git a/panda/src/display/graphicsStateGuardian.cxx b/panda/src/display/graphicsStateGuardian.cxx
index b804613d9e..c55b988125 100644
--- a/panda/src/display/graphicsStateGuardian.cxx
+++ b/panda/src/display/graphicsStateGuardian.cxx
@@ -245,6 +245,7 @@ GraphicsStateGuardian(CoordinateSystem internal_coordinate_system,
   _supports_stencil_wrap = false;
   _supports_two_sided_stencil = false;
   _supports_geometry_instancing = false;
+  _supports_indirect_draw = false;
 
   // Assume a maximum of 1 render target in absence of MRT.
   _max_color_targets = 1;
diff --git a/panda/src/display/graphicsStateGuardian.h b/panda/src/display/graphicsStateGuardian.h
index b657d867e9..50ef6f0f2d 100644
--- a/panda/src/display/graphicsStateGuardian.h
+++ b/panda/src/display/graphicsStateGuardian.h
@@ -160,6 +160,7 @@ PUBLISHED:
   INLINE bool get_supports_stencil() const;
   INLINE bool get_supports_two_sided_stencil() const;
   INLINE bool get_supports_geometry_instancing() const;
+  INLINE bool get_supports_indirect_draw() const;
 
   INLINE bool get_supports_occlusion_query() const;
   INLINE bool get_supports_timer_query() const;
@@ -538,6 +539,7 @@ protected:
   bool _supports_stencil_wrap;
   bool _supports_two_sided_stencil;
   bool _supports_geometry_instancing;
+  bool _supports_indirect_draw;
 
   int _max_color_targets;
 
diff --git a/panda/src/glstuff/glGraphicsStateGuardian_src.cxx b/panda/src/glstuff/glGraphicsStateGuardian_src.cxx
index d24272383c..614dbec469 100644
--- a/panda/src/glstuff/glGraphicsStateGuardian_src.cxx
+++ b/panda/src/glstuff/glGraphicsStateGuardian_src.cxx
@@ -1757,6 +1757,24 @@ reset() {
   }
 #endif
 
+  // Check if we support indirect draw.
+  _supports_indirect_draw = false;
+#ifndef OPENGLES
+  if (is_at_least_gl_version(4, 0) || has_extension("GL_ARB_draw_indirect")) {
+    _glDrawArraysIndirect = (PFNGLDRAWARRAYSINDIRECTPROC)
+      get_extension_func("glDrawArraysIndirect");
+    _glDrawElementsIndirect = (PFNGLDRAWELEMENTSINDIRECTPROC)
+      get_extension_func("glDrawElementsIndirect");
+
+    if (_glDrawArraysIndirect == NULL || _glDrawElementsIndirect == NULL) {
+      GLCAT.warning()
+        << "Indirect draw advertised as supported by OpenGL runtime, but could not get pointers to extension functions.\n";
+    } else {
+      _supports_indirect_draw = true;
+    }
+  }
+#endif
+
 #ifdef OPENGLES_2
   // In OpenGL ES 2.x, FBO's are supported in the core.
   _supports_framebuffer_object = true;
diff --git a/panda/src/glstuff/glGraphicsStateGuardian_src.h b/panda/src/glstuff/glGraphicsStateGuardian_src.h
index fcfe13c56a..62df6fe84c 100644
--- a/panda/src/glstuff/glGraphicsStateGuardian_src.h
+++ b/panda/src/glstuff/glGraphicsStateGuardian_src.h
@@ -763,6 +763,11 @@ public:
   PFNGLDELETEVERTEXARRAYSPROC _glDeleteVertexArrays;
   PFNGLGENVERTEXARRAYSPROC _glGenVertexArrays;
 
+#ifndef OPENGLES
+  PFNGLDRAWARRAYSINDIRECTPROC _glDrawArraysIndirect;
+  PFNGLDRAWELEMENTSINDIRECTPROC _glDrawElementsIndirect;
+#endif
+
   bool _supports_framebuffer_object;
   PFNGLISRENDERBUFFEREXTPROC _glIsRenderbuffer;
   PFNGLBINDRENDERBUFFEREXTPROC _glBindRenderbuffer;