Performance improvement of shadow code, fixed the self-shadowing artifacts, removed push_bias. For infinitely-thin objects, a DepthOffsetAttrib can be applied if necessary.

panda/src/pgraphnodes/lightLensNode.I

@@ -70,14 +70,3 @@ set_shadow_caster(bool caster, int buffer_xsize, int buffer_ysize, int buffer_so
   set_active(caster);
 }
 
-////////////////////////////////////////////////////////////////////
-//     Function: LightLensNode::set_push_bias
-//       Access: Published
-//  Description: Sets the push bias value, this is used to eliminate
-//               depth texture precision errors in shadows. Change
-//               this value if your shadows look strange.
-////////////////////////////////////////////////////////////////////
-INLINE void LightLensNode::
-set_push_bias(float push_bias) {
-  _push_bias = push_bias;
-}

panda/src/pgraphnodes/lightLensNode.cxx

@@ -17,6 +17,9 @@
 #include "bamReader.h"
 #include "datagram.h"
 #include "datagramIterator.h"
+#include "renderState.h"
+#include "cullFaceAttrib.h"
+#include "colorWriteAttrib.h"
 
 TypeHandle LightLensNode::_type_handle;
 
@@ -34,7 +37,9 @@ LightLensNode(const string &name, Lens *lens) :
   _sb_xsize = 512;
   _sb_ysize = 512;
   _sb_sort = -10;
-  _push_bias = 0.5;
+  // Backface culling helps eliminating artifacts.
+  set_initial_state(RenderState::make(CullFaceAttrib::make_reverse(),
+                    ColorWriteAttrib::make(ColorWriteAttrib::C_off)));
 }
 
 ////////////////////////////////////////////////////////////////////
@@ -62,7 +67,9 @@ LightLensNode(const LightLensNode &copy) :
   _sb_xsize = 512;
   _sb_ysize = 512;
   _sb_sort = -10;
-  _push_bias = 0.5;
+  // Backface culling helps eliminating artifacts.
+  set_initial_state(RenderState::make(CullFaceAttrib::make_reverse(),
+                    ColorWriteAttrib::make(ColorWriteAttrib::C_off)));
 }
 
 ////////////////////////////////////////////////////////////////////
@@ -138,7 +145,6 @@ write_datagram(BamWriter *manager, Datagram &dg) {
   dg.add_int32(_sb_xsize);
   dg.add_int32(_sb_ysize);
   dg.add_int32(_sb_sort);
-  dg.add_float64(_push_bias);
 }
 
 ////////////////////////////////////////////////////////////////////
@@ -158,5 +164,5 @@ fillin(DatagramIterator &scan, BamReader *manager) {
   int sb_ysize = scan.get_int32();
   int sb_sort = scan.get_int32();
   set_shadow_caster(shadow_caster, sb_xsize, sb_ysize, sb_sort);
-  set_push_bias(scan.get_float64());
 }
+

panda/src/pgraphnodes/lightLensNode.h

@@ -40,7 +40,6 @@ PUBLISHED:
   INLINE bool is_shadow_caster();
   INLINE void set_shadow_caster(bool caster);
   INLINE void set_shadow_caster(bool caster, int buffer_xsize, int buffer_ysize, int sort = -10);
-  INLINE void set_push_bias(float push_bias);
 
 protected:
   LightLensNode(const LightLensNode &copy);
@@ -48,7 +47,6 @@ protected:
 
   bool _shadow_caster;
   int _sb_xsize, _sb_ysize, _sb_sort;
-  double _push_bias;
 
   // This is really a map of GSG -> GraphicsOutput.
   typedef pmap<PT(GraphicsStateGuardianBase), PT(GraphicsOutputBase) > ShadowBuffers;

panda/src/pgraphnodes/shaderGenerator.cxx

@@ -705,14 +705,12 @@ synthesize_shader(const RenderState *rs) {
     text << "\t float4x4 biasmat = {0.5f, 0.0f, 0.0f, 0.5f, 0.0f, 0.5f, 0.0f, 0.5f, 0.0f, 0.0f, 0.5f, 0.5f, 0.0f, 0.0f, 0.0f, 1.0f};\n";
     for (int i=0; i<(int)_dlights.size(); i++) {
       if (_dlights[i]->_shadow_caster) {
-        text << "\t l_dlightcoord" << i << " = mul(biasmat, mul(trans_model_to_clip_of_dlight"
-          << i << ", vtx_position + " << _dlights[i]->_push_bias << " * vtx_normal));\n";
+        text << "\t l_dlightcoord" << i << " = mul(biasmat, mul(trans_model_to_clip_of_dlight" << i << ", vtx_position));\n";
       }
     }
     for (int i=0; i<(int)_slights.size(); i++) {
       if (_slights[i]->_shadow_caster) {
-        text << "\t l_slightcoord" << i << " = mul(biasmat, mul(trans_model_to_clip_of_slight"
-          << i << ", vtx_position + " << _slights[i]->_push_bias << " * vtx_normal));\n";
+        text << "\t l_slightcoord" << i << " = mul(biasmat, mul(trans_model_to_clip_of_slight" << i << ", vtx_position));\n";
       }
     }
   }