Cookbook: draft docs

docs/cookbook/procgen/05_heightmap_erosion.py

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+"""HeightMap Erosion and Terrain Generation Demo
+
+Demonstrates: rain_erosion, mid_point_displacement, smooth
+Shows natural terrain formation through erosion simulation.
+"""
+import mcrfpy
+from mcrfpy import automation
+
+GRID_WIDTH, GRID_HEIGHT = 64, 48
+CELL_SIZE = 16
+
+def terrain_color(h):
+    """Natural terrain coloring."""
+    if h < 0.2:
+        # Deep water
+        t = h / 0.2
+        return mcrfpy.Color(int(20 + t * 30), int(40 + t * 40), int(100 + t * 55))
+    elif h < 0.3:
+        # Shallow water
+        t = (h - 0.2) / 0.1
+        return mcrfpy.Color(int(50 + t * 50), int(80 + t * 60), int(155 + t * 40))
+    elif h < 0.35:
+        # Beach
+        t = (h - 0.3) / 0.05
+        return mcrfpy.Color(int(194 - t * 30), int(178 - t * 30), int(128 - t * 20))
+    elif h < 0.55:
+        # Lowland grass
+        t = (h - 0.35) / 0.2
+        return mcrfpy.Color(int(80 + t * 20), int(140 - t * 30), int(60 + t * 10))
+    elif h < 0.7:
+        # Highland grass/forest
+        t = (h - 0.55) / 0.15
+        return mcrfpy.Color(int(50 + t * 30), int(100 + t * 10), int(40 + t * 20))
+    elif h < 0.85:
+        # Rock
+        t = (h - 0.7) / 0.15
+        return mcrfpy.Color(int(100 + t * 30), int(95 + t * 30), int(85 + t * 35))
+    else:
+        # Snow
+        t = (h - 0.85) / 0.15
+        return mcrfpy.Color(int(180 + t * 75), int(185 + t * 70), int(190 + t * 65))
+
+def run_demo(runtime):
+    panel_w = GRID_WIDTH // 3
+    panel_h = GRID_HEIGHT // 2
+
+    # Panel 1: Mid-point displacement (raw)
+    mpd_raw = mcrfpy.HeightMap((panel_w, panel_h), fill=0.5)
+    mpd_raw.mid_point_displacement(roughness=0.6, seed=42)
+    mpd_raw.normalize(0.0, 1.0)
+
+    # Panel 2: Mid-point displacement + smoothing
+    mpd_smooth = mcrfpy.HeightMap((panel_w, panel_h), fill=0.5)
+    mpd_smooth.mid_point_displacement(roughness=0.6, seed=42)
+    mpd_smooth.smooth(2)
+    mpd_smooth.normalize(0.0, 1.0)
+
+    # Panel 3: Mid-point + light erosion
+    mpd_light_erode = mcrfpy.HeightMap((panel_w, panel_h), fill=0.5)
+    mpd_light_erode.mid_point_displacement(roughness=0.6, seed=42)
+    mpd_light_erode.rain_erosion(drops=1000, erosion=0.05, sedimentation=0.03, seed=42)
+    mpd_light_erode.normalize(0.0, 1.0)
+
+    # Panel 4: Noise-based + moderate erosion
+    noise = mcrfpy.NoiseSource(dimensions=2, algorithm='simplex', seed=123)
+    noise_erode = mcrfpy.HeightMap((panel_w, panel_h), fill=0.0)
+    noise_erode.add_noise(noise, world_size=(12, 12), mode='fbm', octaves=5)
+    noise_erode.add_hill((panel_w // 2, panel_h // 2), 10, 0.4)
+    noise_erode.rain_erosion(drops=3000, erosion=0.1, sedimentation=0.05, seed=42)
+    noise_erode.normalize(0.0, 1.0)
+
+    # Panel 5: Heavy erosion (river valleys)
+    heavy_erode = mcrfpy.HeightMap((panel_w, panel_h), fill=0.5)
+    heavy_erode.mid_point_displacement(roughness=0.7, seed=99)
+    heavy_erode.rain_erosion(drops=8000, erosion=0.15, sedimentation=0.02, seed=42)
+    heavy_erode.normalize(0.0, 1.0)
+
+    # Panel 6: Extreme erosion (canyon-like)
+    extreme_erode = mcrfpy.HeightMap((panel_w, panel_h), fill=0.5)
+    extreme_erode.mid_point_displacement(roughness=0.5, seed=77)
+    extreme_erode.rain_erosion(drops=15000, erosion=0.2, sedimentation=0.01, seed=42)
+    extreme_erode.smooth(1)
+    extreme_erode.normalize(0.0, 1.0)
+
+    # Apply to grid
+    panels = [
+        (mpd_raw, 0, 0, "MPD Raw"),
+        (mpd_smooth, panel_w, 0, "MPD + Smooth"),
+        (mpd_light_erode, panel_w * 2, 0, "Light Erosion"),
+        (noise_erode, 0, panel_h, "Noise + Erosion"),
+        (heavy_erode, panel_w, panel_h, "Heavy Erosion"),
+        (extreme_erode, panel_w * 2, panel_h, "Extreme Erosion"),
+    ]
+
+    for hmap, ox, oy, name in panels:
+        for y in range(panel_h):
+            for x in range(panel_w):
+                h = hmap.get((x, y))
+                color_layer.set(((ox + x, oy + y)), terrain_color(h))
+
+        label = mcrfpy.Caption(text=name, pos=(ox * CELL_SIZE + 5, oy * CELL_SIZE + 5))
+        label.fill_color = mcrfpy.Color(255, 255, 255)
+        label.outline = 1
+        label.outline_color = mcrfpy.Color(0, 0, 0)
+        scene.children.append(label)
+
+    # Grid lines
+    for y in range(GRID_HEIGHT):
+        color_layer.set(((panel_w - 1, y)), mcrfpy.Color(80, 80, 80))
+        color_layer.set(((panel_w * 2 - 1, y)), mcrfpy.Color(80, 80, 80))
+    for x in range(GRID_WIDTH):
+        color_layer.set(((x, panel_h - 1)), mcrfpy.Color(80, 80, 80))
+
+
+# Setup
+scene = mcrfpy.Scene("erosion_demo")
+
+grid = mcrfpy.Grid(
+    grid_size=(GRID_WIDTH, GRID_HEIGHT),
+    pos=(0, 0),
+    size=(GRID_WIDTH * CELL_SIZE, GRID_HEIGHT * CELL_SIZE),
+    layers={}
+)
+grid.fill_color = mcrfpy.Color(0, 0, 0)
+color_layer = grid.add_layer("color", z_index=-1)
+scene.children.append(grid)
+
+scene.activate()
+
+# Run the demo
+run_demo(0)
+
+# Take screenshot
+automation.screenshot("procgen_05_heightmap_erosion.png")
+print("Screenshot saved: procgen_05_heightmap_erosion.png")