1 files changed, 86 insertions, 0 deletions
diff --git a/libdimension/perspective.c b/libdimension/perspective.c
new file mode 100644
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--- /dev/null
+++ b/libdimension/perspective.c
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+/*************************************************************************
+ * Copyright (C) 2009 Tavian Barnes <tavianator@gmail.com>               *
+ *                                                                       *
+ * This file is part of The Dimension Library.                           *
+ *                                                                       *
+ * The Dimension Library is free software; you can redistribute it and/  *
+ * or modify it under the terms of the GNU Lesser General Public License *
+ * as published by the Free Software Foundation; either version 3 of the *
+ * License, or (at your option) any later version.                       *
+ *                                                                       *
+ * The Dimension Library 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  *
+ * Lesser General Public License for more details.                       *
+ *                                                                       *
+ * You should have received a copy of the GNU Lesser General Public      *
+ * License along with this program.  If not, see                         *
+ * <http://www.gnu.org/licenses/>.                                       *
+ *************************************************************************/
+
+#include "dimension.h"
+
+/*
+ * Perspective camera
+ */
+
+/* Perspective camera ray callback */
+static dmnsn_line dmnsn_perspective_camera_ray_fn(const dmnsn_camera *camera,
+                                                  double x, double y);
+
+/* Create a new perspective camera.  Rays are aimed from the origin to a screen
+   located on the z = 1 frame, from (-0.5, -0.5) to (0.5, 0.5).  Rays are then
+   transformed by the camera's transformation matrix. */
+dmnsn_camera *
+dmnsn_new_perspective_camera()
+{
+  dmnsn_matrix *ptr;
+  dmnsn_camera *camera = dmnsn_new_camera();
+  if (camera) {
+    /* Allocate room for the transformation matrix */
+    ptr = malloc(sizeof(dmnsn_matrix));
+    if (!ptr) {
+      dmnsn_delete_camera(camera);
+      return NULL;
+    }
+    *ptr = dmnsn_identity_matrix();
+
+    camera->ray_fn  = &dmnsn_perspective_camera_ray_fn;
+    camera->free_fn = &free;
+    camera->ptr     = ptr;
+  }
+  return camera;
+}
+
+/* Get the transformation matrix */
+dmnsn_matrix
+dmnsn_get_perspective_camera_trans(const dmnsn_camera *camera)
+{
+  dmnsn_matrix *trans = camera->ptr;
+  return *trans;
+}
+
+/* Set the transformation matrix */
+void
+dmnsn_set_perspective_camera_trans(dmnsn_camera *camera, dmnsn_matrix T)
+{
+  dmnsn_matrix *trans = camera->ptr;
+  *trans = T;
+}
+
+/* Perspective camera ray callback */
+static dmnsn_line
+dmnsn_perspective_camera_ray_fn(const dmnsn_camera *camera,
+                                double x, double y)
+{
+  dmnsn_matrix *trans = camera->ptr;
+  dmnsn_line l;
+
+  /* Rays originate at the origin, oddly enough */
+  l.x0 = dmnsn_new_vector(0.0, 0.0, 0.0);
+
+  /* Aim at the z = 1 plane */
+  l.n  = dmnsn_new_vector(x - 0.5, y - 0.5, 1.0);
+
+  return dmnsn_matrix_line_mul(*trans, l);
+}