Implement initial GJK algorithm.

PiperOrigin-RevId: 645368315
Change-Id: I40a1e1023fd9f14a59e11a9dcc6ac22df241b6ae

src/engine/engine_collision_gjk.h

@@ -0,0 +1,40 @@
+// Copyright 2024 DeepMind Technologies Limited
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef MUJOCO_SRC_ENGINE_ENGINE_COLLISION_GJK_H_
+#define MUJOCO_SRC_ENGINE_ENGINE_COLLISION_GJK_H_
+
+#include <mujoco/mjexport.h>
+#include <mujoco/mjtnum.h>
+#include "engine/engine_collision_convex.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// internal struct with settings for GJK
+struct _mjGjkConfig {
+  mjtNum max_iterations;
+  mjtNum tolerance;
+};
+typedef struct _mjGjkConfig mjGjkConfig;
+
+// Returns the distance between the two objects given an initial guess x0.
+MJAPI mjtNum mj_gjk(const mjGjkConfig* config, mjtCCObj* obj1, mjtCCObj* obj2, const mjtNum x0[3]);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // MUJOCO_SRC_ENGINE_ENGINE_COLLISION_GJK_H_