source/blender/nodes/shader/CMakeLists.txt

@@ -157,6 +157,7 @@ if(WITH_MATERIALX)
     materialx/nodes/tex_image.cc
     materialx/nodes/tex_environment.cc
     materialx/nodes/tex_noise.cc
+    materialx/nodes/tex_checker.cc
 
     materialx/material.h
     materialx/nodes/node_parser.h

source/blender/nodes/shader/materialx/nodes/node_parser.cc

@@ -359,6 +359,13 @@ NodeItem NodeParser::get_input_default(const std::string &name)
     res.value = MaterialX::Value::createValue<int>(v);
     return res;
   }
+  /* Explicit check for Scale socket of Checker Texture node since MaterialX has scales for X and Y axes
+   * and Blender only single. */
+  if (node->typeinfo->type == SH_NODE_TEX_CHECKER && STREQ(socket.name, "Scale")) {
+    float v = socket.default_value_typed<bNodeSocketValueFloat>()->value;
+    res.value = MaterialX::Value::createValue<MaterialX::Vector2>({v, v});
+    return res;
+  }
   switch (socket.type) {
     case SOCK_FLOAT: {
       float v = socket.default_value_typed<bNodeSocketValueFloat>()->value;
@@ -425,6 +432,9 @@ NodeItem NodeParser::get_input_link(const std::string &name)
     case SH_NODE_TEX_NOISE:
       parser = std::make_unique<TexNoiseNodeParser>(graph, depsgraph, material, in_node);
       break;
+    case SH_NODE_TEX_CHECKER:
+      parser = std::make_unique<TexCheckerNodeParser>(graph, depsgraph, material, in_node);
+      break;
     default:
       // TODO: warning log
       return res;

source/blender/nodes/shader/materialx/nodes/node_parser.h

@@ -110,5 +110,6 @@ DECLARE_PARSER(OutputMaterialNodeParser)
 DECLARE_PARSER(TexImageNodeParser)
 DECLARE_PARSER(TexEnvironmentNodeParser)
 DECLARE_PARSER(TexNoiseNodeParser)
+DECLARE_PARSER(TexCheckerNodeParser)
 
 }  // namespace blender::nodes::materialx

source/blender/nodes/shader/materialx/nodes/tex_checker.cc

@@ -0,0 +1,86 @@
+/* SPDX-FileCopyrightText: 2011-2022 Blender Foundation
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "node_parser.h"
+
+#include "hydra/image.h"
+
+#include "DEG_depsgraph_query.h"
+#include <MaterialXFormat/XmlIo.h>
+namespace blender::nodes::materialx {
+
+/* For some reason validator complains about 'octaves' input of 'fractal3d' node (which doesn't even exist here)
+ * and 'in1' input of 'modulo' node, perhaps implementation is fully correct and similar to standart MaterialX
+ * Checkerboard node (added in 1.38.8). Also seems like USD due to lack of support doesn't render this material,
+ * but MaterialX Viewer and GraphEditor do. */
+
+NodeItem TexCheckerNodeParser::compute()
+{
+  Image *image = (Image *)node->id;
+  NodeTexChecker *tex = static_cast<NodeTexChecker *>(node->storage);
+  Scene *scene = DEG_get_input_scene(depsgraph);
+  Main *bmain = DEG_get_bmain(depsgraph);
+
+  NodeItem texcoord = create_node("texcoord", "vector2", true);
+  NodeItem frequency = create_node("constant", "vector2", true);
+  NodeItem scale = get_input_value("Scale");
+
+  /* Modifier to follow Cycles result. */
+  NodeItem scale_fitter(graph);
+  scale_fitter.value = MaterialX::Value::createValue<float>(4.0f);
+  frequency.set_input("value", scale * scale_fitter);
+
+  NodeItem mult = create_node("multiply", "vector2", true);
+  mult.set_input("in1", texcoord);
+  mult.set_input("in2", frequency);
+
+  NodeItem offset = create_node("constant", "vector2", true);
+  offset.set_input("value", MaterialX::Value::createValue<MaterialX::Vector2>({0.0f, 0.0f}));
+
+  NodeItem place2d = create_node("place2d", "vector2", true);
+  place2d.set_input("texcoord", mult);
+  place2d.set_input("offset", offset);
+
+  NodeItem separate = create_node("separate2", "multioutput", true);
+  separate.set_input("in", place2d);
+  separate.node->addOutput("outx", "float");
+  separate.node->addOutput("outy", "float");
+
+  NodeItem modulo_x = create_node("modulo", "float", true);
+  modulo_x.set_input("in1", separate);
+  modulo_x.set_input("in2", MaterialX::Value::createValue<float>(2.0f));
+  modulo_x.node->setConnectedOutput("in1", separate.node->getOutput("outx"));
+
+  NodeItem floor_x = create_node("floor", "float", true);
+  floor_x.set_input("in", modulo_x);
+
+  NodeItem modulo_y = create_node("modulo", "float", true);
+  modulo_y.set_input("in1", separate);
+  modulo_y.set_input("in2", MaterialX::Value::createValue<float>(2.0f));
+  modulo_y.node->setConnectedOutput("in1", separate.node->getOutput("outy"));
+
+  NodeItem floor_y = create_node("floor", "float", true);
+  floor_y.set_input("in", modulo_y);
+
+  NodeItem add = create_node("add", "float", true);
+  add.set_input("in1", floor_x);
+  add.set_input("in2", floor_y);
+
+  NodeItem ifequal = create_node("ifequal", "float", true);
+  ifequal.set_input("value1", add);
+  ifequal.set_input("value2", MaterialX::Value::createValue<float>(1.0f));
+  ifequal.set_input("in1", MaterialX::Value::createValue<float>(1.0f));
+  ifequal.set_input("in2", MaterialX::Value::createValue<float>(0.0f));
+
+  NodeItem mix = create_node("mix", "color3", true);
+  NodeItem color1 = get_input_value("Color1");
+  NodeItem color2 = get_input_value("Color2");
+  mix.set_input("fg", color1.to_color3());
+  mix.set_input("bg", color2.to_color3());
+  mix.set_input("mix", ifequal);
+
+  return mix;
+}
+
+}  // namespace blender::nodes::materialx