SL-20396: Apply blinn-phong rotation to texture translation animations for GLTF materials, for more consistent behavior

1 files changed, 24 insertions, 15 deletions

diff --git a/indra/newview/llvovolume.cpp b/indra/newview/llvovolume.cpp
index 468943423a..f1d4d9039b 100644
--- a/indra/newview/llvovolume.cpp
+++ b/indra/newview/llvovolume.cpp
@@ -666,7 +666,25 @@ void LLVOVolume::animateTextures()
                 {
                     if (!(result & LLViewerTextureAnim::ROTATE))
                     {
-                        rot = 0.0f;
+                        if (result & LLViewerTextureAnim::TRANSLATE)
+                        {
+                            // The current LSL texture animation system is
+                            // based on Blinn-Phong texture transforms, which
+                            // is incompatible with the GLTF texture
+                            // transforms. As a compromise, apply Blinn-Phong
+                            // texture rotation on top of the GLTF texture
+                            // transforms during a translation animation. This
+                            // ensures that the animation loops for trivial
+                            // GLTF texture transforms, when it would for
+                            // similar Blinn-Phong animations. This is not
+                            // guaranteed to loop for nontrivial GLTF texture
+                            // transforms.
+                            te->getRotation(&rot);
+                        }
+                        else
+                        {
+                            rot = 0.0f;
+                        }
                     }
                     if (!(result & LLViewerTextureAnim::TRANSLATE))
                     {
@@ -679,29 +697,20 @@ void LLVOVolume::animateTextures()
                         scale_t = 1.0f;
                     }
 
-                    // For PBR materials, use Blinn-Phong rotation as hint for
-                    // translation direction. In a Blinn-Phong material, the
-                    // translation direction would be a byproduct the texture
-                    // transform.
-                    F32 rot_frame;
-                    te->getRotation(&rot_frame);
-
                     tex_mat.translate(LLVector3(-0.5f, -0.5f, 0.f));
 
                     LLQuaternion quat;
                     quat.setQuat(rot, 0, 0, -1.f);
-                    tex_mat.rotate(quat);				
+                    tex_mat.rotate(quat);
 
                     LLMatrix4 mat;
-                    LLVector3 scale(scale_s, scale_t, 1.f);			
+                    LLVector3 scale(scale_s, scale_t, 1.f);
                     mat.initAll(scale, LLQuaternion(), LLVector3());
                     tex_mat *= mat;
-            
-                    LLVector3 off(off_s, off_t, 0.f);
-                    off.rotVec(rot_frame, 0, 0, 1.f);
-                    tex_mat.translate(off);
 
-                    tex_mat.translate(LLVector3(0.5f, 0.5f, 0.f));
+                    LLVector3 trans;
+                    trans.set(LLVector3(off_s+0.5f, off_t+0.5f, 0.f));
+                    tex_mat.translate(trans);
                 }
 			}
 		}