Merge vertex_util into math_util.

PiperOrigin-RevId: 896071837
Change-Id: Ieec0e4b4b11988805219739a84f413871ae34f1b

Author: haroonq

src/experimental/filament/CMakeLists.txt

@@ -61,8 +61,6 @@ target_sources(${MUJOCO_FILAMENT_TARGET_NAME}
         filament/scene_view.h
         filament/texture.cc
         filament/texture.h
-        filament/vertex_util.cc
-        filament/vertex_util.h
 )
 if(MUJOCO_USE_FILAMENT_MJR_COMPAT)
     target_sources(${MUJOCO_FILAMENT_TARGET_NAME}

src/experimental/filament/filament/builtins.cc

@@ -27,8 +27,8 @@
 #include <math/vec2.h>
 #include <math/vec3.h>
 #include <math/vec4.h>
+#include "experimental/filament/filament/math_util.h"
 #include "experimental/filament/filament/mesh.h"
-#include "experimental/filament/filament/vertex_util.h"
 
 namespace mujoco {
 

src/experimental/filament/filament/math_util.cc

@@ -13,8 +13,11 @@
 // limitations under the License.
 
 #include "experimental/filament/filament/math_util.h"
+#include <limits>
 
+#include <math/mat3.h>
 #include <math/mat4.h>
+#include <math/quat.h>
 #include <math/vec3.h>
 #include <math/vec4.h>
 #include <math/TVecHelpers.h>
@@ -23,7 +26,9 @@ namespace mujoco {
 
 using filament::math::float3;
 using filament::math::float4;
+using filament::math::mat3f;
 using filament::math::mat4;
+using filament::math::quatf;
 
 mat4 ToReflectionMatrix(const mat4& xform) {
   const float3 normal = xform[2].xyz;
@@ -81,4 +86,38 @@ mat4 CalculateObliqueProjection(const mat4& projection, const float4& plane) {
   return res;
 }
 
+
+float4 CalculateOrientation(const float3& normal) {
+  float3 tangent;
+  float3 bitangent;
+  if (normal.y < -1.0f + std::numeric_limits<float>::epsilon()) {
+    // Handle the singularity.
+    tangent = float3{-1.0f, 0.0f, 0.0f};
+    bitangent = float3{0.0f, 0.0f, -1.0f};
+  } else {
+    const float a = 1.0f / (1.0f + normal.y);
+    const float b = -normal.z * normal.x * a;
+    tangent = float3(b, -normal.z, 1.0f - normal.z * normal.z * a);
+    bitangent = float3(1.0f - normal.x * normal.x * a, -normal.x, b);
+  }
+  quatf orientation = mat3f::packTangentFrame({tangent, bitangent, normal});
+  return float4(orientation.xyz, orientation.w);
+}
+
+float3 CalculateNormal(
+    const filament::math::float3& p1,
+    const filament::math::float3& p2,
+    const filament::math::float3& p3) {
+  const float3 v12 = p2 - p1;
+  const float3 v13 = p3 - p1;
+  return normalize(cross(v12, v13));
+}
+
+float4 CalculateOrientation(
+    const filament::math::float3& p1,
+    const filament::math::float3& p2,
+    const filament::math::float3& p3) {
+  return CalculateOrientation(CalculateNormal(p1, p2, p3));
+}
+
 }  // namespace mujoco

src/experimental/filament/filament/math_util.h

@@ -64,6 +64,22 @@ filament::math::mat4 CalculateObliqueProjection(
     const filament::math::mat4& projection,
     const filament::math::float4& plane);
 
+// Calculates the normal of a triangle given its three vertices.
+filament::math::float3 CalculateNormal(
+    const filament::math::float3& p1,
+    const filament::math::float3& p2,
+    const filament::math::float3& p3);
+
+// Calculates the orientation of a vertex given just its normal.
+filament::math::float4 CalculateOrientation(
+    const filament::math::float3& normal);
+
+// Calculates the orientation of a triangle given its three vertices.
+filament::math::float4 CalculateOrientation(
+    const filament::math::float3& p1,
+    const filament::math::float3& p2,
+    const filament::math::float3& p3);
+
 }  // namespace mujoco
 
 #endif  // MUJOCO_SRC_EXPERIMENTAL_FILAMENT_FILAMENT_MATH_UTIL_H_

src/experimental/filament/filament/mesh.cc

@@ -30,7 +30,6 @@
 #include <math/vec4.h>
 #include <mujoco/mujoco.h>
 #include "experimental/filament/filament/math_util.h"
-#include "experimental/filament/filament/vertex_util.h"
 
 namespace mujoco {
 

src/experimental/filament/filament/model_util.cc

@@ -28,7 +28,6 @@
 #include <mujoco/mujoco.h>
 #include "experimental/filament/filament/math_util.h"
 #include "experimental/filament/filament/mesh.h"
-#include "experimental/filament/filament/vertex_util.h"
 
 namespace mujoco {