Grid: add apply_threshold and apply_ranges for HeightMap (closes #199)

Add methods to apply HeightMap data to Grid walkable/transparent properties:
- apply_threshold(source, range, walkable, transparent): Apply properties
  to cells where HeightMap value is in the specified range
- apply_ranges(source, ranges): Apply multiple threshold rules in one pass

Features:
- Size mismatch between HeightMap and Grid raises ValueError
- Both methods return self for chaining
- Uses dynamic type lookup via module for HeightMap type checking
- First matching range wins in apply_ranges
- Cells not matching any range remain unchanged
- TCOD map is synced after changes for FOV/pathfinding

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/UIGrid.cpp

@@ -9,6 +9,7 @@
 #include "PyFOV.h"
 #include "PyPositionHelper.h"  // For standardized position argument parsing
 #include "PyVector.h"  // #179, #181 - For Vector return types
+#include "PyHeightMap.h"  // #199 - HeightMap application methods
 #include <algorithm>
 #include <cmath>    // #142 - for std::floor, std::isnan
 #include <cstring>  // #150 - for strcmp
@@ -1690,6 +1691,229 @@ PyObject* UIGrid::py_center_camera(PyUIGridObject* self, PyObject* args) {
     Py_RETURN_NONE;
 }
 
+// #199 - HeightMap application methods
+
+PyObject* UIGrid::py_apply_threshold(PyUIGridObject* self, PyObject* args, PyObject* kwds) {
+    static const char* keywords[] = {"source", "range", "walkable", "transparent", nullptr};
+    PyObject* source_obj = nullptr;
+    PyObject* range_obj = nullptr;
+    PyObject* walkable_obj = Py_None;
+    PyObject* transparent_obj = Py_None;
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "OO|OO", const_cast<char**>(keywords),
+                                     &source_obj, &range_obj, &walkable_obj, &transparent_obj)) {
+        return nullptr;
+    }
+
+    // Validate source is a HeightMap
+    PyObject* heightmap_type = PyObject_GetAttrString(McRFPy_API::mcrf_module, "HeightMap");
+    if (!heightmap_type) {
+        PyErr_SetString(PyExc_RuntimeError, "HeightMap type not found in module");
+        return nullptr;
+    }
+    bool is_heightmap = PyObject_IsInstance(source_obj, heightmap_type);
+    Py_DECREF(heightmap_type);
+    if (!is_heightmap) {
+        PyErr_SetString(PyExc_TypeError, "source must be a HeightMap");
+        return nullptr;
+    }
+    PyHeightMapObject* hmap = (PyHeightMapObject*)source_obj;
+
+    if (!hmap->heightmap) {
+        PyErr_SetString(PyExc_RuntimeError, "HeightMap not initialized");
+        return nullptr;
+    }
+
+    // Parse range tuple
+    if (!PyTuple_Check(range_obj) || PyTuple_Size(range_obj) != 2) {
+        PyErr_SetString(PyExc_TypeError, "range must be a tuple of (min, max)");
+        return nullptr;
+    }
+
+    float range_min = (float)PyFloat_AsDouble(PyTuple_GetItem(range_obj, 0));
+    float range_max = (float)PyFloat_AsDouble(PyTuple_GetItem(range_obj, 1));
+
+    if (PyErr_Occurred()) {
+        return nullptr;
+    }
+
+    // Check size match
+    if (hmap->heightmap->w != self->data->grid_w || hmap->heightmap->h != self->data->grid_h) {
+        PyErr_Format(PyExc_ValueError,
+            "HeightMap size (%d, %d) does not match Grid size (%d, %d)",
+            hmap->heightmap->w, hmap->heightmap->h, self->data->grid_w, self->data->grid_h);
+        return nullptr;
+    }
+
+    // Parse optional walkable/transparent booleans
+    bool set_walkable = (walkable_obj != Py_None);
+    bool set_transparent = (transparent_obj != Py_None);
+    bool walkable_value = false;
+    bool transparent_value = false;
+
+    if (set_walkable) {
+        walkable_value = PyObject_IsTrue(walkable_obj);
+    }
+    if (set_transparent) {
+        transparent_value = PyObject_IsTrue(transparent_obj);
+    }
+
+    // Apply threshold
+    for (int y = 0; y < self->data->grid_h; y++) {
+        for (int x = 0; x < self->data->grid_w; x++) {
+            float value = TCOD_heightmap_get_value(hmap->heightmap, x, y);
+            if (value >= range_min && value <= range_max) {
+                UIGridPoint& point = self->data->at(x, y);
+                if (set_walkable) {
+                    point.walkable = walkable_value;
+                }
+                if (set_transparent) {
+                    point.transparent = transparent_value;
+                }
+            }
+        }
+    }
+
+    // Sync TCOD map if it exists
+    if (self->data->getTCODMap()) {
+        self->data->syncTCODMap();
+    }
+
+    // Return self for chaining
+    Py_INCREF(self);
+    return (PyObject*)self;
+}
+
+PyObject* UIGrid::py_apply_ranges(PyUIGridObject* self, PyObject* args) {
+    PyObject* source_obj = nullptr;
+    PyObject* ranges_obj = nullptr;
+
+    if (!PyArg_ParseTuple(args, "OO", &source_obj, &ranges_obj)) {
+        return nullptr;
+    }
+
+    // Validate source is a HeightMap
+    PyObject* heightmap_type = PyObject_GetAttrString(McRFPy_API::mcrf_module, "HeightMap");
+    if (!heightmap_type) {
+        PyErr_SetString(PyExc_RuntimeError, "HeightMap type not found in module");
+        return nullptr;
+    }
+    bool is_heightmap = PyObject_IsInstance(source_obj, heightmap_type);
+    Py_DECREF(heightmap_type);
+    if (!is_heightmap) {
+        PyErr_SetString(PyExc_TypeError, "source must be a HeightMap");
+        return nullptr;
+    }
+    PyHeightMapObject* hmap = (PyHeightMapObject*)source_obj;
+
+    if (!hmap->heightmap) {
+        PyErr_SetString(PyExc_RuntimeError, "HeightMap not initialized");
+        return nullptr;
+    }
+
+    // Validate ranges is a list
+    if (!PyList_Check(ranges_obj)) {
+        PyErr_SetString(PyExc_TypeError, "ranges must be a list");
+        return nullptr;
+    }
+
+    // Check size match
+    if (hmap->heightmap->w != self->data->grid_w || hmap->heightmap->h != self->data->grid_h) {
+        PyErr_Format(PyExc_ValueError,
+            "HeightMap size (%d, %d) does not match Grid size (%d, %d)",
+            hmap->heightmap->w, hmap->heightmap->h, self->data->grid_w, self->data->grid_h);
+        return nullptr;
+    }
+
+    // Parse all ranges first to catch errors early
+    struct RangeEntry {
+        float min, max;
+        bool set_walkable, set_transparent;
+        bool walkable_value, transparent_value;
+    };
+    std::vector<RangeEntry> entries;
+
+    Py_ssize_t num_ranges = PyList_Size(ranges_obj);
+    for (Py_ssize_t i = 0; i < num_ranges; i++) {
+        PyObject* entry = PyList_GetItem(ranges_obj, i);
+
+        if (!PyTuple_Check(entry) || PyTuple_Size(entry) != 2) {
+            PyErr_Format(PyExc_TypeError,
+                "ranges[%zd] must be a tuple of (range, properties_dict)", i);
+            return nullptr;
+        }
+
+        PyObject* range_tuple = PyTuple_GetItem(entry, 0);
+        PyObject* props_dict = PyTuple_GetItem(entry, 1);
+
+        if (!PyTuple_Check(range_tuple) || PyTuple_Size(range_tuple) != 2) {
+            PyErr_Format(PyExc_TypeError,
+                "ranges[%zd] range must be a tuple of (min, max)", i);
+            return nullptr;
+        }
+
+        if (!PyDict_Check(props_dict)) {
+            PyErr_Format(PyExc_TypeError,
+                "ranges[%zd] properties must be a dict", i);
+            return nullptr;
+        }
+
+        RangeEntry re;
+        re.min = (float)PyFloat_AsDouble(PyTuple_GetItem(range_tuple, 0));
+        re.max = (float)PyFloat_AsDouble(PyTuple_GetItem(range_tuple, 1));
+
+        if (PyErr_Occurred()) {
+            return nullptr;
+        }
+
+        // Parse walkable from dict
+        PyObject* walkable_val = PyDict_GetItemString(props_dict, "walkable");
+        re.set_walkable = (walkable_val != nullptr);
+        if (re.set_walkable) {
+            re.walkable_value = PyObject_IsTrue(walkable_val);
+        }
+
+        // Parse transparent from dict
+        PyObject* transparent_val = PyDict_GetItemString(props_dict, "transparent");
+        re.set_transparent = (transparent_val != nullptr);
+        if (re.set_transparent) {
+            re.transparent_value = PyObject_IsTrue(transparent_val);
+        }
+
+        entries.push_back(re);
+    }
+
+    // Apply all ranges in a single pass
+    for (int y = 0; y < self->data->grid_h; y++) {
+        for (int x = 0; x < self->data->grid_w; x++) {
+            float value = TCOD_heightmap_get_value(hmap->heightmap, x, y);
+            UIGridPoint& point = self->data->at(x, y);
+
+            // Check each range (first match wins)
+            for (const auto& re : entries) {
+                if (value >= re.min && value <= re.max) {
+                    if (re.set_walkable) {
+                        point.walkable = re.walkable_value;
+                    }
+                    if (re.set_transparent) {
+                        point.transparent = re.transparent_value;
+                    }
+                    break;  // First matching range wins
+                }
+            }
+        }
+    }
+
+    // Sync TCOD map if it exists
+    if (self->data->getTCODMap()) {
+        self->data->syncTCODMap();
+    }
+
+    // Return self for chaining
+    Py_INCREF(self);
+    return (PyObject*)self;
+}
+
 PyMethodDef UIGrid::methods[] = {
     {"at", (PyCFunction)UIGrid::py_at, METH_VARARGS | METH_KEYWORDS},
     {"compute_fov", (PyCFunction)UIGrid::py_compute_fov, METH_VARARGS | METH_KEYWORDS,
@@ -1759,6 +1983,35 @@ PyMethodDef UIGrid::methods[] = {
      "    grid.center_camera()        # Center on middle of grid\n"
      "    grid.center_camera((5, 10)) # Center on tile (5, 10)\n"
      "    grid.center_camera((0, 0))  # Center on tile (0, 0)"},
+    // #199 - HeightMap application methods
+    {"apply_threshold", (PyCFunction)UIGrid::py_apply_threshold, METH_VARARGS | METH_KEYWORDS,
+     "apply_threshold(source: HeightMap, range: tuple, walkable: bool = None, transparent: bool = None) -> Grid\n\n"
+     "Apply walkable/transparent properties where heightmap values are in range.\n\n"
+     "Args:\n"
+     "    source: HeightMap with values to check. Must match grid size.\n"
+     "    range: Tuple of (min, max) - cells with values in this range are affected.\n"
+     "    walkable: If not None, set walkable to this value for cells in range.\n"
+     "    transparent: If not None, set transparent to this value for cells in range.\n\n"
+     "Returns:\n"
+     "    Grid: self, for method chaining.\n\n"
+     "Raises:\n"
+     "    ValueError: If HeightMap size doesn't match grid size."},
+    {"apply_ranges", (PyCFunction)UIGrid::py_apply_ranges, METH_VARARGS,
+     "apply_ranges(source: HeightMap, ranges: list) -> Grid\n\n"
+     "Apply multiple thresholds in a single pass.\n\n"
+     "Args:\n"
+     "    source: HeightMap with values to check. Must match grid size.\n"
+     "    ranges: List of (range_tuple, properties_dict) tuples.\n"
+     "            range_tuple: (min, max) value range\n"
+     "            properties_dict: {'walkable': bool, 'transparent': bool}\n\n"
+     "Returns:\n"
+     "    Grid: self, for method chaining.\n\n"
+     "Example:\n"
+     "    grid.apply_ranges(terrain, [\n"
+     "        ((0.0, 0.3), {'walkable': False, 'transparent': True}),   # Water\n"
+     "        ((0.3, 0.8), {'walkable': True, 'transparent': True}),    # Land\n"
+     "        ((0.8, 1.0), {'walkable': False, 'transparent': False}),  # Mountains\n"
+     "    ])"},
     {NULL, NULL, 0, NULL}
 };
 
@@ -1851,6 +2104,35 @@ PyMethodDef UIGrid_all_methods[] = {
      "    grid.center_camera()        # Center on middle of grid\n"
      "    grid.center_camera((5, 10)) # Center on tile (5, 10)\n"
      "    grid.center_camera((0, 0))  # Center on tile (0, 0)"},
+    // #199 - HeightMap application methods
+    {"apply_threshold", (PyCFunction)UIGrid::py_apply_threshold, METH_VARARGS | METH_KEYWORDS,
+     "apply_threshold(source: HeightMap, range: tuple, walkable: bool = None, transparent: bool = None) -> Grid\n\n"
+     "Apply walkable/transparent properties where heightmap values are in range.\n\n"
+     "Args:\n"
+     "    source: HeightMap with values to check. Must match grid size.\n"
+     "    range: Tuple of (min, max) - cells with values in this range are affected.\n"
+     "    walkable: If not None, set walkable to this value for cells in range.\n"
+     "    transparent: If not None, set transparent to this value for cells in range.\n\n"
+     "Returns:\n"
+     "    Grid: self, for method chaining.\n\n"
+     "Raises:\n"
+     "    ValueError: If HeightMap size doesn't match grid size."},
+    {"apply_ranges", (PyCFunction)UIGrid::py_apply_ranges, METH_VARARGS,
+     "apply_ranges(source: HeightMap, ranges: list) -> Grid\n\n"
+     "Apply multiple thresholds in a single pass.\n\n"
+     "Args:\n"
+     "    source: HeightMap with values to check. Must match grid size.\n"
+     "    ranges: List of (range_tuple, properties_dict) tuples.\n"
+     "            range_tuple: (min, max) value range\n"
+     "            properties_dict: {'walkable': bool, 'transparent': bool}\n\n"
+     "Returns:\n"
+     "    Grid: self, for method chaining.\n\n"
+     "Example:\n"
+     "    grid.apply_ranges(terrain, [\n"
+     "        ((0.0, 0.3), {'walkable': False, 'transparent': True}),   # Water\n"
+     "        ((0.3, 0.8), {'walkable': True, 'transparent': True}),    # Land\n"
+     "        ((0.8, 1.0), {'walkable': False, 'transparent': False}),  # Mountains\n"
+     "    ])"},
     {NULL}  // Sentinel
 };
 

src/UIGrid.h

@@ -179,6 +179,10 @@ public:
     static PyObject* py_entities_in_radius(PyUIGridObject* self, PyObject* args, PyObject* kwds);  // #115
     static PyObject* py_center_camera(PyUIGridObject* self, PyObject* args);  // #169
 
+    // #199 - HeightMap application methods
+    static PyObject* py_apply_threshold(PyUIGridObject* self, PyObject* args, PyObject* kwds);
+    static PyObject* py_apply_ranges(PyUIGridObject* self, PyObject* args);
+
     // #169 - Camera positioning
     void center_camera();  // Center on grid's middle tile
     void center_camera(float tile_x, float tile_y);  // Center on specific tile

tests/unit/test_grid_apply.py

@@ -0,0 +1,310 @@
+#!/usr/bin/env python3
+"""Unit tests for Grid.apply_threshold and Grid.apply_ranges (#199)
+
+Tests the Grid methods for applying HeightMap data to walkable/transparent properties.
+"""
+
+import sys
+import mcrfpy
+
+
+def test_apply_threshold_walkable():
+    """apply_threshold sets walkable property correctly"""
+    grid = mcrfpy.Grid(grid_size=(10, 10))
+    hmap = mcrfpy.HeightMap((10, 10), fill=0.5)
+
+    # All cells start with default walkable
+    grid.apply_threshold(hmap, range=(0.0, 1.0), walkable=True)
+
+    # Check a few cells
+    assert grid.at((5, 5)).walkable == True
+    assert grid.at((0, 0)).walkable == True
+    assert grid.at((9, 9)).walkable == True
+    print("PASS: test_apply_threshold_walkable")
+
+
+def test_apply_threshold_transparent():
+    """apply_threshold sets transparent property correctly"""
+    grid = mcrfpy.Grid(grid_size=(10, 10))
+    hmap = mcrfpy.HeightMap((10, 10), fill=0.5)
+
+    grid.apply_threshold(hmap, range=(0.0, 1.0), transparent=False)
+
+    assert grid.at((5, 5)).transparent == False
+    print("PASS: test_apply_threshold_transparent")
+
+
+def test_apply_threshold_both():
+    """apply_threshold sets both walkable and transparent"""
+    grid = mcrfpy.Grid(grid_size=(10, 10))
+    hmap = mcrfpy.HeightMap((10, 10), fill=0.5)
+
+    grid.apply_threshold(hmap, range=(0.0, 1.0), walkable=True, transparent=True)
+
+    point = grid.at((5, 5))
+    assert point.walkable == True
+    assert point.transparent == True
+    print("PASS: test_apply_threshold_both")
+
+
+def test_apply_threshold_out_of_range():
+    """apply_threshold doesn't affect cells outside range"""
+    grid = mcrfpy.Grid(grid_size=(10, 10))
+    hmap = mcrfpy.HeightMap((10, 10), fill=0.5)
+
+    # Set initial state
+    grid.at((5, 5)).walkable = False
+    grid.at((5, 5)).transparent = False
+
+    # Apply threshold with range that excludes 0.5
+    grid.apply_threshold(hmap, range=(0.0, 0.4), walkable=True, transparent=True)
+
+    # Cell should remain unchanged
+    assert grid.at((5, 5)).walkable == False
+    assert grid.at((5, 5)).transparent == False
+    print("PASS: test_apply_threshold_out_of_range")
+
+
+def test_apply_threshold_returns_self():
+    """apply_threshold returns self for chaining"""
+    grid = mcrfpy.Grid(grid_size=(10, 10))
+    hmap = mcrfpy.HeightMap((10, 10), fill=0.5)
+
+    result = grid.apply_threshold(hmap, range=(0.0, 1.0), walkable=True)
+    assert result is grid, "apply_threshold should return self"
+    print("PASS: test_apply_threshold_returns_self")
+
+
+def test_apply_threshold_size_mismatch():
+    """apply_threshold raises ValueError for size mismatch"""
+    grid = mcrfpy.Grid(grid_size=(10, 10))
+    hmap = mcrfpy.HeightMap((20, 20), fill=0.5)
+
+    try:
+        grid.apply_threshold(hmap, range=(0.0, 1.0), walkable=True)
+        print("FAIL: test_apply_threshold_size_mismatch - should have raised ValueError")
+        sys.exit(1)
+    except ValueError as e:
+        assert "size" in str(e).lower()
+
+    print("PASS: test_apply_threshold_size_mismatch")
+
+
+def test_apply_threshold_invalid_source():
+    """apply_threshold raises TypeError for non-HeightMap source"""
+    grid = mcrfpy.Grid(grid_size=(10, 10))
+
+    try:
+        grid.apply_threshold("not a heightmap", range=(0.0, 1.0), walkable=True)
+        print("FAIL: test_apply_threshold_invalid_source - should have raised TypeError")
+        sys.exit(1)
+    except TypeError:
+        pass
+
+    print("PASS: test_apply_threshold_invalid_source")
+
+
+def test_apply_threshold_none_values():
+    """apply_threshold with None values leaves properties unchanged"""
+    grid = mcrfpy.Grid(grid_size=(10, 10))
+    hmap = mcrfpy.HeightMap((10, 10), fill=0.5)
+
+    # Set initial state
+    grid.at((5, 5)).walkable = True
+    grid.at((5, 5)).transparent = False
+
+    # Apply with only walkable=False, transparent should stay unchanged
+    grid.apply_threshold(hmap, range=(0.0, 1.0), walkable=False)
+
+    assert grid.at((5, 5)).walkable == False
+    assert grid.at((5, 5)).transparent == False  # Unchanged
+    print("PASS: test_apply_threshold_none_values")
+
+
+def test_apply_ranges_basic():
+    """apply_ranges applies multiple ranges correctly"""
+    grid = mcrfpy.Grid(grid_size=(10, 10))
+    hmap = mcrfpy.HeightMap((10, 10), fill=0.5)
+
+    # Apply a range that covers 0.5
+    grid.apply_ranges(hmap, [
+        ((0.4, 0.6), {"walkable": True, "transparent": True}),
+    ])
+
+    assert grid.at((5, 5)).walkable == True
+    assert grid.at((5, 5)).transparent == True
+    print("PASS: test_apply_ranges_basic")
+
+
+def test_apply_ranges_first_match_wins():
+    """apply_ranges uses first matching range"""
+    grid = mcrfpy.Grid(grid_size=(10, 10))
+    hmap = mcrfpy.HeightMap((10, 10), fill=0.5)
+
+    # Both ranges cover 0.5, first should win
+    grid.apply_ranges(hmap, [
+        ((0.0, 0.6), {"walkable": True}),
+        ((0.4, 1.0), {"walkable": False}),
+    ])
+
+    assert grid.at((5, 5)).walkable == True  # First match wins
+    print("PASS: test_apply_ranges_first_match_wins")
+
+
+def test_apply_ranges_returns_self():
+    """apply_ranges returns self for chaining"""
+    grid = mcrfpy.Grid(grid_size=(10, 10))
+    hmap = mcrfpy.HeightMap((10, 10), fill=0.5)
+
+    result = grid.apply_ranges(hmap, [
+        ((0.0, 1.0), {"walkable": True}),
+    ])
+    assert result is grid, "apply_ranges should return self"
+    print("PASS: test_apply_ranges_returns_self")
+
+
+def test_apply_ranges_size_mismatch():
+    """apply_ranges raises ValueError for size mismatch"""
+    grid = mcrfpy.Grid(grid_size=(10, 10))
+    hmap = mcrfpy.HeightMap((5, 5), fill=0.5)
+
+    try:
+        grid.apply_ranges(hmap, [
+            ((0.0, 1.0), {"walkable": True}),
+        ])
+        print("FAIL: test_apply_ranges_size_mismatch - should have raised ValueError")
+        sys.exit(1)
+    except ValueError as e:
+        assert "size" in str(e).lower()
+
+    print("PASS: test_apply_ranges_size_mismatch")
+
+
+def test_apply_ranges_empty_list():
+    """apply_ranges with empty list doesn't change anything"""
+    grid = mcrfpy.Grid(grid_size=(10, 10))
+    hmap = mcrfpy.HeightMap((10, 10), fill=0.5)
+
+    grid.at((5, 5)).walkable = True
+    grid.at((5, 5)).transparent = False
+
+    grid.apply_ranges(hmap, [])
+
+    # Should remain unchanged
+    assert grid.at((5, 5)).walkable == True
+    assert grid.at((5, 5)).transparent == False
+    print("PASS: test_apply_ranges_empty_list")
+
+
+def test_apply_ranges_no_match():
+    """apply_ranges leaves cells unchanged when no range matches"""
+    grid = mcrfpy.Grid(grid_size=(10, 10))
+    hmap = mcrfpy.HeightMap((10, 10), fill=0.5)
+
+    grid.at((5, 5)).walkable = True
+    grid.at((5, 5)).transparent = True
+
+    # Ranges that don't include 0.5
+    grid.apply_ranges(hmap, [
+        ((0.0, 0.4), {"walkable": False}),
+        ((0.6, 1.0), {"transparent": False}),
+    ])
+
+    # Should remain unchanged
+    assert grid.at((5, 5)).walkable == True
+    assert grid.at((5, 5)).transparent == True
+    print("PASS: test_apply_ranges_no_match")
+
+
+def test_apply_ranges_invalid_format():
+    """apply_ranges raises TypeError for invalid format"""
+    grid = mcrfpy.Grid(grid_size=(10, 10))
+    hmap = mcrfpy.HeightMap((10, 10), fill=0.5)
+
+    # Invalid: not a list
+    try:
+        grid.apply_ranges(hmap, "not a list")
+        print("FAIL: should have raised TypeError for non-list")
+        sys.exit(1)
+    except TypeError:
+        pass
+
+    # Invalid: entry not a tuple
+    try:
+        grid.apply_ranges(hmap, ["not a tuple"])
+        print("FAIL: should have raised TypeError for non-tuple entry")
+        sys.exit(1)
+    except TypeError:
+        pass
+
+    # Invalid: range not a tuple
+    try:
+        grid.apply_ranges(hmap, [
+            ([0.0, 1.0], {"walkable": True}),  # list instead of tuple for range
+        ])
+        print("FAIL: should have raised TypeError for non-tuple range")
+        sys.exit(1)
+    except TypeError:
+        pass
+
+    # Invalid: props not a dict
+    try:
+        grid.apply_ranges(hmap, [
+            ((0.0, 1.0), "not a dict"),
+        ])
+        print("FAIL: should have raised TypeError for non-dict props")
+        sys.exit(1)
+    except TypeError:
+        pass
+
+    print("PASS: test_apply_ranges_invalid_format")
+
+
+def test_chaining():
+    """Methods can be chained together"""
+    grid = mcrfpy.Grid(grid_size=(10, 10))
+    hmap = mcrfpy.HeightMap((10, 10))
+
+    # Chain multiple operations
+    hmap.fill(0.5)
+
+    result = (grid
+              .apply_threshold(hmap, range=(0.0, 0.4), walkable=False)
+              .apply_threshold(hmap, range=(0.6, 1.0), transparent=False)
+              .apply_ranges(hmap, [
+                  ((0.4, 0.6), {"walkable": True, "transparent": True}),
+              ]))
+
+    assert result is grid
+    print("PASS: test_chaining")
+
+
+def run_all_tests():
+    """Run all tests"""
+    print("Running Grid apply method tests...")
+    print()
+
+    test_apply_threshold_walkable()
+    test_apply_threshold_transparent()
+    test_apply_threshold_both()
+    test_apply_threshold_out_of_range()
+    test_apply_threshold_returns_self()
+    test_apply_threshold_size_mismatch()
+    test_apply_threshold_invalid_source()
+    test_apply_threshold_none_values()
+    test_apply_ranges_basic()
+    test_apply_ranges_first_match_wins()
+    test_apply_ranges_returns_self()
+    test_apply_ranges_size_mismatch()
+    test_apply_ranges_empty_list()
+    test_apply_ranges_no_match()
+    test_apply_ranges_invalid_format()
+    test_chaining()
+
+    print()
+    print("All Grid apply method tests PASSED!")
+
+
+# Run tests directly
+run_all_tests()
+sys.exit(0)