read: Clarify openage usage of alpha values.

SFTtech · Feb 28, 2023 · dc5c6b5 · dc5c6b5
1 parent 757883a
commit dc5c6b5
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Showing 3 changed files with 15 additions and 5 deletions.
diff --git a/openage/convert/value_object/read/media/slp.pyx b/openage/convert/value_object/read/media/slp.pyx
@@ -1541,7 +1541,9 @@ cdef numpy.ndarray determine_rgba_matrix(vector[vector[pixel]] &image_matrix,
                 r, g, b = 0, 0, 0
                 alpha = 255 - (px_val << 2)
 
-                # Only odd alphas are used in openage; even alphas are used for commands
+                # change alpha values to match openage texture formats
+                # even alphas are used for commands marking *special* pixels (player color, etc.)
+                # odd alphas are used for normal pixels (= displayed as-is with transparency)
                 alpha = alpha | 0x01
 
             else:
@@ -1611,7 +1613,9 @@ cdef numpy.ndarray determine_rgba_matrix32(vector[vector[pixel32]] &image_matrix
                 b = px.b
                 alpha = px.a
 
-                # Only odd alphas are used in openage; even alphas are used for commands
+                # change alpha values to match openage texture formats
+                # even alphas are used for commands marking *special* pixels (player color, etc.)
+                # odd alphas are used for normal pixels (= displayed as-is with transparency)
                 alpha = alpha | 0x01
 
             elif px_type == color_transparent:
@@ -1624,7 +1628,9 @@ cdef numpy.ndarray determine_rgba_matrix32(vector[vector[pixel32]] &image_matrix
                 r, g, b = 0, 0, 0
                 alpha = 255 - (px.r << 2)
 
-                # Only odd alphas are used in openage; even alphas are used for commands
+                # change alpha values to match openage texture formats
+                # even alphas are used for commands marking *special* pixels (player color, etc.)
+                # odd alphas are used for normal pixels (= displayed as-is with transparency)
                 alpha = alpha | 0x01
 
             else:

diff --git a/openage/convert/value_object/read/media/smp.pyx b/openage/convert/value_object/read/media/smp.pyx
@@ -815,7 +815,9 @@ cdef numpy.ndarray determine_rgba_matrix(vector[vector[pixel]] &image_matrix,
             elif px_type == color_shadow:
                 r, g, b, alpha = 0, 0, 0, px_index
 
-                # Only odd alphas are used in openage; even alphas are used for commands
+                # change alpha values to match openage texture formats
+                # even alphas are used for commands marking *special* pixels (player color, etc.)
+                # odd alphas are used for normal pixels (= displayed as-is with transparency)
                 alpha = alpha | 0x01
 
             else:

diff --git a/openage/convert/value_object/read/media/smx.pyx b/openage/convert/value_object/read/media/smx.pyx
@@ -1112,7 +1112,9 @@ cdef numpy.ndarray determine_rgba_matrix(vector[vector[pixel]] &image_matrix,
             elif px_type == color_shadow:
                 r, g, b, alpha = 0, 0, 0, px_index
 
-                # Only odd alphas are used in openage; even alphas are used for commands
+                # change alpha values to match openage texture formats
+                # even alphas are used for commands marking *special* pixels (player color, etc.)
+                # odd alphas are used for normal pixels (= displayed as-is with transparency)
                 alpha = alpha | 0x01
 
             else: