From b786b486b6c05e7bcdef53f6086daae179ffd6e3 Mon Sep 17 00:00:00 2001
From: Ben Doherty <bendoherty@google.com>
Date: Wed, 22 Jul 2020 15:12:03 -0700
Subject: [PATCH] Add getCullingProjectionMatrix JNI method (#2847)

---
 .../filament-android/src/main/cpp/Camera.cpp  | 10 ++++++
 .../com/google/android/filament/Camera.java   | 31 +++++++++++++++++--
 filament/include/filament/Camera.h            |  2 +-
 3 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/android/filament-android/src/main/cpp/Camera.cpp b/android/filament-android/src/main/cpp/Camera.cpp
index 2e54e0b11d..347eb00e71 100644
--- a/android/filament-android/src/main/cpp/Camera.cpp
+++ b/android/filament-android/src/main/cpp/Camera.cpp
@@ -103,6 +103,16 @@ Java_com_google_android_filament_Camera_nGetProjectionMatrix(JNIEnv *env, jclass
     env->ReleaseDoubleArrayElements(out_, out, 0);
 }
 
+extern "C" JNIEXPORT void JNICALL
+Java_com_google_android_filament_Camera_nGetCullingProjectionMatrix(JNIEnv *env, jclass,
+        jlong nativeCamera, jdoubleArray out_) {
+    Camera *camera = (Camera *) nativeCamera;
+    jdouble *out = env->GetDoubleArrayElements(out_, NULL);
+    const filament::math::mat4& m = camera->getCullingProjectionMatrix();
+    std::copy_n(&m[0][0], 16, out);
+    env->ReleaseDoubleArrayElements(out_, out, 0);
+}
+
 extern "C" JNIEXPORT void JNICALL
 Java_com_google_android_filament_Camera_nGetScaling(JNIEnv *env, jclass,
         jlong nativeCamera, jdoubleArray out_) {
diff --git a/android/filament-android/src/main/java/com/google/android/filament/Camera.java b/android/filament-android/src/main/java/com/google/android/filament/Camera.java
index b1394e9a6d..d7c1723d6d 100644
--- a/android/filament-android/src/main/java/com/google/android/filament/Camera.java
+++ b/android/filament-android/src/main/java/com/google/android/filament/Camera.java
@@ -284,7 +284,15 @@ public class Camera {
      * ratio:<br>
      *
      * <code>
-     *     camera->setScaling(double4 {1.0, width / height, 1.0, 1.0});
+     *     double aspect = width / height;
+     *
+     *     // with Fov.HORIZONTAL passed to setProjection:
+     *     double[] s = {1.0, aspect, 1.0, 1.0};
+     *     camera.setScaling(s);
+     *
+     *     // with Fov.VERTICAL passed to setProjection:
+     *     double[] s = {1.0 / aspect, 1.0, 1.0, 1.0};
+     *     camera.setScaling(s);
      * </code>
      *
      * By default, this is an identity matrix.
@@ -354,7 +362,9 @@ public class Camera {
     }
 
     /**
-     * Retrieves the camera's projection matrix.
+     * Retrieves the camera's projection matrix. The projection matrix used for rendering always has
+     * its far plane set to infinity. This is why it may differ from the matrix set through
+     * setProjection() or setLensProjection().
      *
      * @param out A 16-float array where the projection matrix will be stored, or null in which
      *            case a new array is allocated.
@@ -368,6 +378,22 @@ public class Camera {
         return out;
     }
 
+    /**
+     * Retrieves the camera's culling matrix. The culling matrix is the same as the projection
+     * matrix, except the far plane is finite.
+     *
+     * @param out A 16-float array where the projection matrix will be stored, or null in which
+     *            case a new array is allocated.
+     *
+     * @return A 16-float array containing the camera's projection as a column-major matrix.
+     */
+    @NonNull @Size(min = 16)
+    public double[] getCullingProjectionMatrix(@Nullable @Size(min = 16) double[] out) {
+        out = Asserts.assertMat4d(out);
+        nGetCullingProjectionMatrix(getNativeObject(), out);
+        return out;
+    }
+
     /**
      * Returns the scaling amount used to scale the projection matrix.
      *
@@ -566,6 +592,7 @@ public class Camera {
     private static native float nGetNear(long nativeCamera);
     private static native float nGetCullingFar(long nativeCamera);
     private static native void nGetProjectionMatrix(long nativeCamera, double[] out);
+    private static native void nGetCullingProjectionMatrix(long nativeCamera, double[] out);
     private static native void nGetScaling(long nativeCamera, double[] out);
     private static native void nGetModelMatrix(long nativeCamera, float[] out);
     private static native void nGetViewMatrix(long nativeCamera, float[] out);
diff --git a/filament/include/filament/Camera.h b/filament/include/filament/Camera.h
index d7bdeec616..60ecd042dc 100644
--- a/filament/include/filament/Camera.h
+++ b/filament/include/filament/Camera.h
@@ -232,7 +232,7 @@ public:
     /** Returns the projection matrix used for rendering.
      *
      * The projection matrix used for rendering always has its far plane set to infinity. This
-     * it why it may differ from the matrix set through setProjection() or setLensProjection().
+     * is why it may differ from the matrix set through setProjection() or setLensProjection().
      *
      * @return The projection matrix used for rendering
      *