Add FRUSTUM camera mode, allowing tilted frustums

This new camera mode makes it easy to create tilted frustums for mirror
or portal effects.

This work was kindly sponsored by IMVU.

4 files changed, 28 insertions, 1 deletions

diff --git a/servers/visual/visual_server_raster.h b/servers/visual/visual_server_raster.h
index 89a759b963..2248f15c19 100644
--- a/servers/visual/visual_server_raster.h
+++ b/servers/visual/visual_server_raster.h
@@ -429,6 +429,7 @@ public:
 	BIND0R(RID, camera_create)
 	BIND4(camera_set_perspective, RID, float, float, float)
 	BIND4(camera_set_orthogonal, RID, float, float, float)
+	BIND5(camera_set_frustum, RID, float, Vector2, float, float)
 	BIND2(camera_set_transform, RID, const Transform &)
 	BIND2(camera_set_cull_mask, RID, uint32_t)
 	BIND2(camera_set_environment, RID, RID)
diff --git a/servers/visual/visual_server_scene.cpp b/servers/visual/visual_server_scene.cpp
index 5d0456686a..abf13c57a5 100644
--- a/servers/visual/visual_server_scene.cpp
+++ b/servers/visual/visual_server_scene.cpp
@@ -61,6 +61,16 @@ void VisualServerScene::camera_set_orthogonal(RID p_camera, float p_size, float
 	camera->zfar = p_z_far;
 }
 
+void VisualServerScene::camera_set_frustum(RID p_camera, float p_size, Vector2 p_offset, float p_z_near, float p_z_far) {
+	Camera *camera = camera_owner.get(p_camera);
+	ERR_FAIL_COND(!camera);
+	camera->type = Camera::FRUSTUM;
+	camera->size = p_size;
+	camera->offset = p_offset;
+	camera->znear = p_z_near;
+	camera->zfar = p_z_far;
+}
+
 void VisualServerScene::camera_set_transform(RID p_camera, const Transform &p_transform) {
 
 	Camera *camera = camera_owner.get(p_camera);
@@ -1720,6 +1730,17 @@ void VisualServerScene::render_camera(RID p_camera, RID p_scenario, Size2 p_view
 			ortho = false;
 
 		} break;
+		case Camera::FRUSTUM: {
+
+			camera_matrix.set_frustum(
+					camera->size,
+					p_viewport_size.width / (float)p_viewport_size.height,
+					camera->offset,
+					camera->znear,
+					camera->zfar,
+					camera->vaspect);
+			ortho = false;
+		} break;
 	}
 
 	_prepare_scene(camera->transform, camera_matrix, ortho, camera->env, camera->visible_layers, p_scenario, p_shadow_atlas, RID());
diff --git a/servers/visual/visual_server_scene.h b/servers/visual/visual_server_scene.h
index 7583acd88f..2c2ba7e15f 100644
--- a/servers/visual/visual_server_scene.h
+++ b/servers/visual/visual_server_scene.h
@@ -77,12 +77,14 @@ public:
 
 		enum Type {
 			PERSPECTIVE,
-			ORTHOGONAL
+			ORTHOGONAL,
+			FRUSTUM
 		};
 		Type type;
 		float fov;
 		float znear, zfar;
 		float size;
+		Vector2 offset;
 		uint32_t visible_layers;
 		bool vaspect;
 		RID env;
@@ -97,6 +99,7 @@ public:
 			znear = 0.05;
 			zfar = 100;
 			size = 1.0;
+			offset = Vector2();
 			vaspect = false;
 		}
 	};
@@ -106,6 +109,7 @@ public:
 	virtual RID camera_create();
 	virtual void camera_set_perspective(RID p_camera, float p_fovy_degrees, float p_z_near, float p_z_far);
 	virtual void camera_set_orthogonal(RID p_camera, float p_size, float p_z_near, float p_z_far);
+	virtual void camera_set_frustum(RID p_camera, float p_size, Vector2 p_offset, float p_z_near, float p_z_far);
 	virtual void camera_set_transform(RID p_camera, const Transform &p_transform);
 	virtual void camera_set_cull_mask(RID p_camera, uint32_t p_layers);
 	virtual void camera_set_environment(RID p_camera, RID p_env);
diff --git a/servers/visual/visual_server_wrap_mt.h b/servers/visual/visual_server_wrap_mt.h
index a6f0bd9d16..a35afe6e87 100644
--- a/servers/visual/visual_server_wrap_mt.h
+++ b/servers/visual/visual_server_wrap_mt.h
@@ -359,6 +359,7 @@ public:
 	FUNCRID(camera)
 	FUNC4(camera_set_perspective, RID, float, float, float)
 	FUNC4(camera_set_orthogonal, RID, float, float, float)
+	FUNC5(camera_set_frustum, RID, float, Vector2, float, float)
 	FUNC2(camera_set_transform, RID, const Transform &)
 	FUNC2(camera_set_cull_mask, RID, uint32_t)
 	FUNC2(camera_set_environment, RID, RID)