1 files changed, 94 insertions, 0 deletions
diff --git a/io_scene_gltf2/blender/exp/gltf2_blender_texture_specular.py b/io_scene_gltf2/blender/exp/gltf2_blender_texture_specular.py
new file mode 100644
index 00000000..6321f128
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+++ b/io_scene_gltf2/blender/exp/gltf2_blender_texture_specular.py
@@ -0,0 +1,94 @@
+# SPDX-License-Identifier: Apache-2.0
+# Copyright 2018-2022 The glTF-Blender-IO authors.
+
+import bpy
+import numpy as np
+from .gltf2_blender_gather_image import StoreImage, StoreData
+from .gltf2_blender_image import TmpImageGuard, make_temp_image_copy
+
+def specular_calculation(stored):
+
+    # See https://gist.github.com/proog128/d627c692a6bbe584d66789a5a6437a33
+    
+    # Find all Blender images used
+    images = []
+    for fill in stored.values():
+        if isinstance(fill, StoreImage):
+            if fill.image not in images:
+                images.append(fill.image)
+
+    if not images:
+        # No ImageFills; use a 1x1 white pixel
+        pixels = np.array([1.0, 1.0, 1.0, 1.0], np.float32)
+        return pixels, 1, 1
+
+    width = max(image.size[0] for image in images)
+    height = max(image.size[1] for image in images)
+
+    buffers = {}
+
+    for identifier, image in [(ident, store.image) for (ident, store) in stored.items() if isinstance(store, StoreImage)]:
+        tmp_buf = np.empty(width * height * 4, np.float32)
+        
+        if image.size[0] == width and image.size[1] == height:
+            image.pixels.foreach_get(tmp_buf)
+        else:
+            # Image is the wrong size; make a temp copy and scale it.
+            with TmpImageGuard() as guard:
+                make_temp_image_copy(guard, src_image=image)
+                tmp_image = guard.image
+                tmp_image.scale(width, height)
+                tmp_image.pixels.foreach_get(tmp_buf)
+
+        buffers[identifier] = np.reshape(tmp_buf, [width, height, 4])
+
+    # keep only needed channels
+    ## scalar
+    for i in ['specular', 'specular_tint', 'transmission']:
+        if i in buffers.keys():
+            buffers[i] = buffers[i][:,:,stored[i + "_channel"].data]
+        else:
+            buffers[i] = np.full((width, height, 1), stored[i].data)
+
+    # Vector 3
+    for i in ['base_color']:
+        if i in buffers.keys():
+            if i + "_channel" not in stored.keys():
+                buffers[i] = buffers[i][:,:,:3]
+            else:
+                # keep only needed channel
+                for c in range(3):
+                    if c != stored[i+"_channel"].data:
+                        buffers[i][:, :, c] = 0.0
+                buffers[i] = buffers[i][:,:,:3]
+        else:
+            buffers[i] = np.full((width, height, 3), stored[i].data[0:3])
+
+    ior = stored['ior'].data
+
+    # calculation
+    stack3 = lambda v: np.dstack([v]*3)
+
+    def normalize(c):
+        luminance = lambda c: 0.3 * c[:,:,0] + 0.6 * c[:,:,1] + 0.1 * c[:,:,2]
+        l = luminance(c)
+        # TODOExt Manage all 0
+        return c / stack3(l)
+
+    
+    f0_from_ior = ((ior - 1)/(ior + 1))**2
+    tint_strength = (1 - stack3(buffers['specular_tint'])) + normalize(buffers['base_color']) * stack3(buffers['specular_tint'])
+    out_buf = (1 - stack3(buffers['transmission'])) * (1 / f0_from_ior) * 0.08 * stack3(buffers['specular']) * tint_strength + stack3(buffers['transmission']) * tint_strength
+
+    # Manage values > 1.0 -> Need to apply factor
+    factor = None
+    factors = [np.amax(out_buf[:, :, i]) for i in range(3)]
+
+    if any([f > 1.0 for f in factors]):
+        factor = [1.0 if f < 1.0 else f for f in factors]
+        out_buf /= factor
+
+    out_buf = np.dstack((out_buf, np.ones((width, height)))) # Set alpha (glTF specular) to 1
+    out_buf = np.reshape(out_buf, (width * height * 4))
+    
+    return np.float32(out_buf), width, height, [float(f) for f in factor] if factor else None