1 files changed, 62 insertions, 0 deletions
diff --git a/indra/newview/app_settings/shaders/class1/interface/pbrTerrainBakeF.glsl b/indra/newview/app_settings/shaders/class1/interface/pbrTerrainBakeF.glsl
new file mode 100644
index 0000000000..cf20653a0f
--- /dev/null
+++ b/indra/newview/app_settings/shaders/class1/interface/pbrTerrainBakeF.glsl
@@ -0,0 +1,62 @@
+/**
+ * @file terrainBakeF.glsl
+ *
+ * $LicenseInfo:firstyear=2007&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2024, Linden Research, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+/*[EXTRA_CODE_HERE]*/
+
+out vec4 frag_color;
+
+struct TerrainMix
+{
+    vec4 weight;
+    int type;
+};
+
+TerrainMix get_terrain_mix_weights(float alpha1, float alpha2, float alphaFinal);
+
+uniform sampler2D alpha_ramp;
+
+// vary_texcoord* are used for terrain composition
+in vec4 vary_texcoord0;
+in vec4 vary_texcoord1;
+
+void main()
+{
+    TerrainMix tm;
+    float alpha1 = texture(alpha_ramp, vary_texcoord0.zw).a;
+    float alpha2 = texture(alpha_ramp,vary_texcoord1.xy).a;
+    float alphaFinal = texture(alpha_ramp, vary_texcoord1.zw).a;
+
+    tm = get_terrain_mix_weights(alpha1, alpha2, alphaFinal);
+
+    // tm.weight.x can be ignored. The paintmap saves a channel by not storing
+    // swatch 1, and assuming the weights of the 4 swatches add to 1.
+    // TERRAIN_PAINT_PRECISION emulates loss of precision at lower bit depth
+    // when a corresponding low-bit image format is not available. Because
+    // integral values at one depth cannot be precisely represented at another
+    // bit depth, rounding is required. To maximize numerical stability for
+    // future conversions, bit depth conversions should round to the nearest
+    // integer, not floor or ceil.
+    frag_color = max(vec4(round(tm.weight.yzw * TERRAIN_PAINT_PRECISION) / TERRAIN_PAINT_PRECISION, 1.0), vec4(0));
+}