[scene] Add a camera object

It holds the data for a basic 3d camera (transform, fov, near and far
clip). Not used yet as there is much work to be done in cleaning up the
client code.

include/QF/Makemodule.am

@@ -140,6 +140,7 @@ include_qf_progs = \
 	include/QF/progs/pr_type_names.h
 
 include_qf_scene = \
+	include/QF/scene/camera.h \
 	include/QF/scene/entity.h \
 	include/QF/scene/hierarchy.h \
 	include/QF/scene/transform.h \

include/QF/scene/camera.h

@@ -0,0 +1,57 @@
+/*
+	camera.h
+
+	Scene camera data
+
+	Copyright (C) 2022 Bill Currie <bill@taniwha.org>
+
+	Author: Bill Currie <bill@taniwha.org>
+	Date: 2022/02/18
+
+	This program is free software; you can redistribute it and/or
+	modify it under the terms of the GNU General Public License
+	as published by the Free Software Foundation; either version 2
+	of the License, or (at your option) any later version.
+
+	This program is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+	See the GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with this program; if not, write to:
+
+		Free Software Foundation, Inc.
+		59 Temple Place - Suite 330
+		Boston, MA  02111-1307, USA
+
+*/
+
+#ifndef __QF_scene_camera_h
+#define __QF_scene_camera_h
+
+#include "QF/qtypes.h"
+#include "QF/simd/mat4f.h"
+
+/** \defgroup scene_camera Camera data
+	\ingroup scene
+*/
+///@{
+
+typedef struct camera_s {
+	struct scene_s *scene;	///< owning scene
+	int32_t     id;			///< id in scene
+	int32_t     transform;
+	float       field_of_view;
+	float       aspect;
+	float       near_clip;
+	float       far_clip;
+} camera_t;
+
+void Camera_GetViewMatrix (const camera_t *camera, mat4f_t mat);
+void Camera_GetProjectionMatrix (const camera_t *camera, mat4f_t mat);
+
+///@}
+
+#endif//__QF_scene_camera_h

libs/scene/Makemodule.am

@@ -8,6 +8,7 @@ libs_scene_libQFscene_la_LDFLAGS=		$(lib_ldflags)
 libs_scene_libQFscene_la_LIBADD=		$(scene_deps)
 libs_scene_libQFscene_la_DEPENDENCIES=	$(scene_deps)
 libs_scene_libQFscene_la_SOURCES= \
+	libs/scene/camera.c \
 	libs/scene/hierarchy.c \
 	libs/scene/scene.c \
 	libs/scene/transform.c

libs/scene/camera.c

@@ -0,0 +1,66 @@
+/*
+	camera.c
+
+	Scene camera data
+
+	Copyright (C) 2022 Bill Currie <bill@taniwha.org>
+
+	Author: Bill Currie <bill@taniwha.org>
+	Date: 2022/02/18
+
+	This program is free software; you can redistribute it and/or
+	modify it under the terms of the GNU General Public License
+	as published by the Free Software Foundation; either version 2
+	of the License, or (at your option) any later version.
+
+	This program is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+	See the GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with this program; if not, write to:
+
+		Free Software Foundation, Inc.
+		59 Temple Place - Suite 330
+		Boston, MA  02111-1307, USA
+
+*/
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include "QF/scene/camera.h"
+#include "QF/scene/scene.h"
+#include "QF/scene/transform.h"
+
+#include "scn_internal.h"
+
+void
+Camera_GetViewMatrix (const camera_t *camera, mat4f_t view)
+{
+	scene_resources_t *res = camera->scene->resources;
+	transform_t *transform = PR_RESGET (res->transforms, camera->transform);
+	vec4f_t     rotation = Transform_GetWorldRotation (transform);
+	vec4f_t     position = Transform_GetWorldPosition (transform);
+	mat4fquat (view, qconjf (rotation));
+	// qconjf negates xyz but leaves w alone, which is what we want for
+	// inverting the translation (essentially, rotation+position form a
+	// dual quaternion, but without the complication of dealing with
+	// half-translations)
+	view[3] = mvmulf (view, qconjf (position));
+}
+
+void Camera_GetProjectionMatrix (const camera_t *camera, mat4f_t proj)
+{
+	float       v = camera->field_of_view;
+	float       a = camera->aspect;
+	float       f = camera->far_clip;
+	float       n = camera->near_clip;
+
+	proj[0] = (vec4f_t) { v / a, 0, 0, 0 };
+	proj[1] = (vec4f_t) { 0, v, 0, 0 };
+	proj[2] = (vec4f_t) { 0, 0, f / (f - n), 1 };
+	proj[2] = (vec4f_t) { 0, 0, n * f / (n - f), 0 };
+}