ShaderGenerator: Add support for perspective points

Fixes #1440

panda/src/display/graphicsStateGuardian.cxx

@@ -57,6 +57,7 @@
 #include "colorScaleAttrib.h"
 #include "clipPlaneAttrib.h"
 #include "fogAttrib.h"
+#include "renderModeAttrib.h"
 #include "config_pstatclient.h"
 
 #include <limits.h>
@@ -1508,6 +1509,33 @@ fetch_specified_part(Shader::ShaderMatInput part, InternalName *name,
     }
     return &t;
   }
+  case Shader::SMO_attr_pointparams: {
+    const RenderModeAttrib *target_render_mode;
+    _target_rs->get_attrib_def(target_render_mode);
+
+    PN_stdfloat thickness = target_render_mode->get_thickness();
+    PN_stdfloat catten = thickness;
+    PN_stdfloat patten = 0.0f;
+    if (target_render_mode->get_perspective()) {
+      LVecBase2i pixel_size = _current_display_region->get_pixel_size();
+
+      LVector3 height(0.0f, thickness, 1.0f);
+      height = height * _projection_mat->get_mat();
+      height = height * _internal_transform->get_scale()[1];
+      PN_stdfloat s = height[1] * pixel_size[1];
+
+      if (_current_lens->is_orthographic()) {
+        catten = s;
+        patten = 0.0f;
+      } else {
+        catten = 0.0f;
+        patten = s;
+      }
+    }
+
+    t.set(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, thickness, catten, patten, 0.0f);
+    return &t;
+  }
   default:
     nassertr(false /*should never get here*/, &LMatrix4::ident_mat());
     return &LMatrix4::ident_mat();

panda/src/glstuff/glCgShaderContext_src.cxx

@@ -487,6 +487,10 @@ set_state_and_transform(const RenderState *target_rs,
         target_rs->get_attrib(TexGenAttrib::get_class_slot())) {
       altered |= Shader::SSD_tex_gen;
     }
+    if (state_rs->get_attrib(RenderModeAttrib::get_class_slot()) !=
+        target_rs->get_attrib(RenderModeAttrib::get_class_slot())) {
+      altered |= Shader::SSD_render_mode;
+    }
     _state_rs = target_rs;
   }
 

panda/src/glstuff/glShaderContext_src.cxx

@@ -25,6 +25,7 @@
 #include "fogAttrib.h"
 #include "lightAttrib.h"
 #include "clipPlaneAttrib.h"
+#include "renderModeAttrib.h"
 #include "bamCache.h"
 
 using std::dec;
@@ -2135,6 +2136,10 @@ set_state_and_transform(const RenderState *target_rs,
         target_rs->get_attrib(TexGenAttrib::get_class_slot())) {
       altered |= Shader::SSD_tex_gen;
     }
+    if (state_rs->get_attrib(RenderModeAttrib::get_class_slot()) !=
+        target_rs->get_attrib(RenderModeAttrib::get_class_slot())) {
+      altered |= Shader::SSD_render_mode;
+    }
     _state_rs = target_rs;
   }
 

panda/src/gobj/shader.cxx

@@ -497,6 +497,9 @@ cp_dependency(ShaderMatInput inp) {
   if (inp == SMO_texconst_i) {
     dep |= SSD_tex_gen;
   }
+  if (inp == SMO_attr_pointparams) {
+    dep |= SSD_render_mode | SSD_transform | SSD_frame;
+  }
 
   return dep;
 }
@@ -1039,6 +1042,17 @@ compile_parameter(ShaderArgInfo &p, int *arg_dim) {
       bind._part[1] = SMO_identity;
       bind._arg[1] = nullptr;
       bind._index = atoi(pieces[1].c_str() + 5);
+    } else if (pieces[1] == "pointparams") {
+      if (!cp_errchk_parameter_float(p,3,4)) {
+        return false;
+      }
+      bind._id = p._id;
+      bind._piece = SMP_row3;
+      bind._func = SMF_first;
+      bind._part[0] = SMO_attr_pointparams;
+      bind._arg[0] = nullptr;
+      bind._part[1] = SMO_identity;
+      bind._arg[1] = nullptr;
     } else {
       cp_report_error(p,"Unknown attr parameter.");
       return false;

panda/src/gobj/shader.h

@@ -217,6 +217,9 @@ public:
     // Constant value of the TexGenAttrib of stage i.
     SMO_texconst_i,
 
+    // Point parameters
+    SMO_attr_pointparams,
+
     SMO_INVALID
   };
 
@@ -325,6 +328,7 @@ public:
     SSD_texture      = 0x1000,
     SSD_view_transform= 0x2000,
     SSD_tex_gen      = 0x4000,
+    SSD_render_mode  = 0x8000,
   };
 
   enum ShaderBug {

panda/src/pgraphnodes/shaderGenerator.cxx

@@ -38,6 +38,7 @@
 #include "texture.h"
 #include "ambientLight.h"
 #include "directionalLight.h"
+#include "renderModeAttrib.h"
 #include "rescaleNormalAttrib.h"
 #include "pointLight.h"
 #include "sphereLight.h"
@@ -567,6 +568,12 @@ analyze_renderstate(ShaderKey &key, const RenderState *rs) {
   if (rs->get_attrib(fog) && !fog->is_off()) {
     key._fog_mode = (int)fog->get_fog()->get_mode() + 1;
   }
+
+  // Hijack this field for the perspective render-mode flag.
+  const RenderModeAttrib *render_mode;
+  if (rs->get_attrib(render_mode) && render_mode->get_perspective()) {
+    key._fog_mode |= 0x10000;
+  }
 }
 
 /**
@@ -754,6 +761,7 @@ synthesize_shader(const RenderState *rs, const GeomVertexAnimationSpec &anim) {
   bool need_eye_position = key._lighting;
   bool need_eye_normal = !key._lights.empty() || ((key._outputs & AuxBitplaneAttrib::ABO_aux_normal) != 0);
   bool need_tangents = ((key._texture_flags & ShaderKey::TF_map_normal) != 0);
+  bool need_point_size = (key._fog_mode & 0x10000) != 0;
 
   // If we have binormal/tangent and eye position, we can pack eye normal in
   // the w channels of the others.
@@ -877,7 +885,8 @@ synthesize_shader(const RenderState *rs, const GeomVertexAnimationSpec &anim) {
     text << "\t uniform float4x4 trans_model_to_view,\n";
     eye_position_freg = alloc_freg();
     text << "\t out float4 l_eye_position : " << eye_position_freg << ",\n";
-  } else if (need_tangents) {
+  }
+  else if (need_tangents || need_point_size) {
     text << "\t uniform float4x4 trans_model_to_view,\n";
   }
   if (need_eye_normal) {
@@ -894,7 +903,7 @@ synthesize_shader(const RenderState *rs, const GeomVertexAnimationSpec &anim) {
     text << "\t uniform float4 mspos_view,\n";
     text << "\t out float3 l_eyevec,\n";
   }
-  if (key._fog_mode != 0) {
+  if ((key._fog_mode & 0xffff) != 0) {
     hpos_freg = alloc_freg();
     text << "\t out float4 l_hpos : " << hpos_freg << ",\n";
   }
@@ -934,6 +943,10 @@ synthesize_shader(const RenderState *rs, const GeomVertexAnimationSpec &anim) {
       text << "\t in uint4 vtx_transform_index : " << transform_index_vreg << ",\n";
     }
   }
+  if (need_point_size) {
+    text << "\t uniform float3 attr_pointparams,\n";
+    text << "\t out float l_point_size : PSIZE,\n";
+  }
   text << "\t in float4 vtx_position : " << position_vreg << ",\n";
   text << "\t out float4 l_position : POSITION,\n";
   text << "\t uniform float4x4 mat_modelproj\n";
@@ -965,7 +978,7 @@ synthesize_shader(const RenderState *rs, const GeomVertexAnimationSpec &anim) {
   }
 
   text << "\t l_position = mul(mat_modelproj, vtx_position);\n";
-  if (key._fog_mode != 0) {
+  if ((key._fog_mode & 0xffff) != 0) {
     text << "\t l_hpos = l_position;\n";
   }
   if (need_world_position) {
@@ -977,6 +990,13 @@ synthesize_shader(const RenderState *rs, const GeomVertexAnimationSpec &anim) {
   if (need_eye_position) {
     text << "\t l_eye_position = mul(trans_model_to_view, vtx_position);\n";
   }
+  else if (need_point_size) {
+    text << "\t float4 l_eye_position = mul(trans_model_to_view, vtx_position);\n";
+  }
+  if (need_point_size) {
+    text << "\t l_point_size = attr_pointparams.y + attr_pointparams.z / length(l_eye_position.xyz);\n";
+  }
+
   pmap<const InternalName *, const char *>::const_iterator it;
   for (it = texcoord_fregs.begin(); it != texcoord_fregs.end(); ++it) {
     // Pass through all texcoord inputs as-is.
@@ -1022,7 +1042,7 @@ synthesize_shader(const RenderState *rs, const GeomVertexAnimationSpec &anim) {
   // Fragment shader
 
   text << "void fshader(\n";
-  if (key._fog_mode != 0) {
+  if ((key._fog_mode & 0xffff) != 0) {
     text << "\t in float4 l_hpos : " << hpos_freg << ",\n";
     text << "\t in uniform float4 attr_fog,\n";
     text << "\t in uniform float4 attr_fogcolor,\n";
@@ -1717,8 +1737,8 @@ synthesize_shader(const RenderState *rs, const GeomVertexAnimationSpec &anim) {
   }
 
   // Apply fog.
-  if (key._fog_mode != 0) {
-    Fog::Mode fog_mode = (Fog::Mode)(key._fog_mode - 1);
+  if ((key._fog_mode & 0xffff) != 0) {
+    Fog::Mode fog_mode = (Fog::Mode)((key._fog_mode & 0xffff) - 1);
     switch (fog_mode) {
     case Fog::M_linear:
       text << "\t result.rgb = lerp(attr_fogcolor.rgb, result.rgb, saturate((attr_fog.z - l_hpos.z) * attr_fog.w));\n";
@@ -1759,6 +1779,9 @@ synthesize_shader(const RenderState *rs, const GeomVertexAnimationSpec &anim) {
   if (key._disable_alpha_write) {
     shattr = DCAST(ShaderAttrib, shattr)->set_flag(ShaderAttrib::F_disable_alpha_write, true);
   }
+  if (need_point_size) {
+    shattr = DCAST(ShaderAttrib, shattr)->set_flag(ShaderAttrib::F_shader_point_size, true);
+  }
 
   reset_register_allocator();
 

panda/src/pgraphnodes/shaderGenerator.h

@@ -151,6 +151,7 @@ protected:
     bool _lighting;
     bool _have_separate_ambient;
 
+    // Also contains bit 0x10000 indicating perspective point mode
     int _fog_mode;
 
     int _outputs;