ShaderGenerator: use shadow map filtering for point light shadows

We were never able to use this because of bugs in the Cg Toolkit, but now that we're no longer using that, we're free to use it.

panda/src/display/graphicsStateGuardian.cxx

@@ -3494,9 +3494,13 @@ get_dummy_shadow_map(Texture::TextureType texture_type) const {
       dummy_cube = new Texture("dummy-shadow-cube");
       dummy_cube->setup_cube_map(1, Texture::T_unsigned_byte, Texture::F_depth_component);
       dummy_cube->set_clear_color(1);
-      // Note: cube map shadow filtering doesn't seem to work in Cg.
-      dummy_cube->set_minfilter(SamplerState::FT_linear);
-      dummy_cube->set_magfilter(SamplerState::FT_linear);
+      if (get_supports_shadow_filter()) {
+        dummy_cube->set_minfilter(SamplerState::FT_shadow);
+        dummy_cube->set_magfilter(SamplerState::FT_shadow);
+      } else {
+        dummy_cube->set_minfilter(SamplerState::FT_linear);
+        dummy_cube->set_magfilter(SamplerState::FT_linear);
+      }
     }
     return dummy_cube;
   }

panda/src/pgraphnodes/pointLight.cxx

@@ -208,10 +208,8 @@ setup_shadow_map() {
   _shadow_map->set_clear_color(LColor(1));
   _shadow_map->set_wrap_u(SamplerState::WM_clamp);
   _shadow_map->set_wrap_v(SamplerState::WM_clamp);
-
-  // Note: cube map shadow filtering doesn't seem to work in Cg.
-  _shadow_map->set_minfilter(SamplerState::FT_linear);
-  _shadow_map->set_magfilter(SamplerState::FT_linear);
+  _shadow_map->set_minfilter(SamplerState::FT_shadow);
+  _shadow_map->set_magfilter(SamplerState::FT_shadow);
 }
 
 /**

panda/src/pgraphnodes/shaderGenerator.cxx

@@ -1051,11 +1051,17 @@ synthesize_shader(const RenderState *rs, const GeomVertexAnimationSpec &anim) {
     const ShaderKey::LightInfo &light = key._lights[i];
     if (light._flags & ShaderKey::LF_has_shadows) {
       if (light._type.is_derived_from(PointLight::get_class_type())) {
-        text << "\t uniform samplerCUBE shadow_" << i << ",\n";
-      } else if (_use_shadow_filter) {
-        text << "\t uniform sampler2DShadow shadow_" << i << ",\n";
+        if (_use_shadow_filter) {
+          text << "\t uniform samplerCubeShadow shadow_" << i << ",\n";
+        } else {
+          text << "\t uniform samplerCUBE shadow_" << i << ",\n";
+        }
       } else {
-        text << "\t uniform sampler2D shadow_" << i << ",\n";
+        if (_use_shadow_filter) {
+          text << "\t uniform sampler2DShadow shadow_" << i << ",\n";
+        } else {
+          text << "\t uniform sampler2D shadow_" << i << ",\n";
+        }
       }
       if (lightcoord_fregs[i] != nullptr) {
         text << "\t in float4 l_lightcoord" << i << " : " << lightcoord_fregs[i] << ",\n";
@@ -1352,7 +1358,11 @@ synthesize_shader(const RenderState *rs, const GeomVertexAnimationSpec &anim) {
       if (light._flags & ShaderKey::LF_has_shadows) {
         text << "\t ldist = max(abs(l_lightcoord" << i << ".x), max(abs(l_lightcoord" << i << ".y), abs(l_lightcoord" << i << ".z)));\n";
         text << "\t ldist = ((latten.w+lpoint.w)/(latten.w-lpoint.w))+((-2*latten.w*lpoint.w)/(ldist * (latten.w-lpoint.w)));\n";
-        text << "\t lshad = texCUBE(shadow_" << i << ", l_lightcoord" << i << ".xyz).r >= ldist * 0.5 + 0.5;\n";
+        if (_use_shadow_filter) {
+          text << "\t lshad = shadowCube(shadow_" << i << ", float4(l_lightcoord" << i << ".xyz, ldist * 0.5 + 0.5)).r;\n";
+        } else {
+          text << "\t lshad = texCUBE(shadow_" << i << ", l_lightcoord" << i << ".xyz).r >= ldist * 0.5 + 0.5;\n";
+        }
         text << "\t lcolor *= lshad;\n";
         text << "\t lspec *= lshad;\n";
       }