ANARI: use intensity values for ply point clouds

Author: Daniel Wickeroth

src/OpenCOVER/plugins/ukoeln/ANARI/readPLY.h

@@ -3,12 +3,21 @@
 // std
 #include <cassert>
 #include <iostream>
+#include <algorithm>
+#include <cctype>
 // anari
 #include <anari/anari_cpp.hpp>
 #include <anari/anari_cpp/ext/glm.h>
 // rply
 #include "rply.h"
 
+inline std::string toLower(const std::string& str) {
+  std::string lower = str;
+  std::transform(lower.begin(), lower.end(), lower.begin(),
+                 [](unsigned char c){ return std::tolower(c); });
+  return lower;
+}
+
 inline int rplyReadVertexCallback(p_ply_argument arg)
 {
   long axis;
@@ -41,6 +50,25 @@ inline int rplyReadColorCallback(p_ply_argument arg)
   return 1;
 }
 
+inline int rplyReadIntensityCallback(p_ply_argument arg)
+{
+  long axis;
+  void *pointer;
+  ply_get_argument_user_data(arg, &pointer, &axis);
+  auto **colors = (glm::vec3 **)pointer;
+  float val = ply_get_argument_value(arg);
+
+  static unsigned long count = 0;
+  // Normalize intensity to 0-1 range (assuming it's 0-255, adjust if needed)
+  float normalized = val > 1.0f ? val/255.f : val;
+  (*colors)[count][0] = normalized;
+  (*colors)[count][1] = normalized;
+  (*colors)[count][2] = normalized;
+  count++;
+
+  return 1;
+}
+
 anari::Surface readPLY(anari::Device device, std::string fn, float radius)
 {
   p_ply ply = ply_open(fn.c_str(), NULL, 0, NULL);
@@ -50,14 +78,58 @@ anari::Surface readPLY(anari::Device device, std::string fn, float radius)
   }
 
   glm::vec3 *positions = nullptr, *colors = nullptr;
-  
+
+  // Detect what color data is available
+  bool hasVertexColors = false;
+  std::string intensityPropertyName;
+
+  // Check for vertex colors (red, green, blue)
+  p_ply_element element = nullptr;
+  while ((element = ply_get_next_element(ply, element))) {
+    const char *elemName;
+    long nInstances;
+    ply_get_element_info(element, &elemName, &nInstances);
+
+    if (std::string(elemName) == "vertex") {
+      p_ply_property property = nullptr;
+      bool hasRed = false, hasGreen = false, hasBlue = false;
+
+      while ((property = ply_get_next_property(element, property))) {
+        const char *propName;
+        ply_get_property_info(property, &propName, nullptr, nullptr, nullptr);
+        std::string propNameStr(propName);
+
+        if (propNameStr == "red") hasRed = true;
+        if (propNameStr == "green") hasGreen = true;
+        if (propNameStr == "blue") hasBlue = true;
+
+        // Check for intensity property (case-insensitive)
+        if (intensityPropertyName.empty() &&
+            toLower(propNameStr).find("intensity") != std::string::npos) {
+          intensityPropertyName = propNameStr;
+        }
+      }
+
+      hasVertexColors = hasRed && hasGreen && hasBlue;
+      break;
+    }
+  }
+
   long numSpheres = ply_set_read_cb(ply, "vertex", "x", rplyReadVertexCallback, &positions, 0);
   ply_set_read_cb(ply, "vertex", "y", rplyReadVertexCallback, &positions, 1);
   ply_set_read_cb(ply, "vertex", "z", rplyReadVertexCallback, &positions, 2);
 
-  ply_set_read_cb(ply, "vertex", "red", rplyReadColorCallback, &colors, 0);
-  ply_set_read_cb(ply, "vertex", "green", rplyReadColorCallback, &colors, 1);
-  ply_set_read_cb(ply, "vertex", "blue", rplyReadColorCallback, &colors, 2);
+  // Set up color callbacks based on what's available
+  if (hasVertexColors) {
+    std::cout << "ANARI::Using vertex colors from PLY file.\n";
+    ply_set_read_cb(ply, "vertex", "red", rplyReadColorCallback, &colors, 0);
+    ply_set_read_cb(ply, "vertex", "green", rplyReadColorCallback, &colors, 1);
+    ply_set_read_cb(ply, "vertex", "blue", rplyReadColorCallback, &colors, 2);
+  } else if (!intensityPropertyName.empty()) {
+    std::cout << "ANARI::Using intensity property '" << intensityPropertyName << "' for grayscale colors from PLY file.\n";
+    ply_set_read_cb(ply, "vertex", intensityPropertyName.c_str(),
+                    rplyReadIntensityCallback, &colors, 0);
+  }
 
   auto positionsArray =
       anari::newArray1D(device, ANARI_FLOAT32_VEC3, numSpheres);
@@ -68,6 +140,14 @@ anari::Surface readPLY(anari::Device device, std::string fn, float radius)
   positions = anari::map<glm::vec3>(device, positionsArray);
   colors = anari::map<glm::vec3>(device, colorsArray);
 
+  // If no color data will be read, initialize with medium gray
+  if (!hasVertexColors && intensityPropertyName.empty()) {
+    std::cout << "ANARI::No color information found in PLY file. Using default gray color.\n";
+    for (long i = 0; i < numSpheres; ++i) {
+      colors[i] = glm::vec3(0.5f, 0.5f, 0.5f);
+    }
+  }
+
   if (!ply_read(ply)) {
     std::cerr << "Cound not read file: " << fn << '\n';
     return nullptr;