star-camera

commit d4c87487761880a1037e984ed7fe4180090059a2
parent 0d482412d2db4d86d212c302f10fe219f8f37ec7
Author: Vincent Forest <vincent.forest@meso-star.com>
Date:   Thu,  1 Jul 2021 12:50:31 +0200

Implement the scam_generate_ray function

Diffstat:
M
src/scam.c
 | 
50
++++++++++++++++++++++++++++++++++++++++++++++++++
M
src/scam.h
 | 
21
+++++++++++++++++++++
M
src/scam_c.h
 | 
7
++++++-
M
src/scam_pinhole.c
 | 
24
++++++++++++++++++++++++

4 files changed, 101 insertions(+), 1 deletion(-)
diff --git a/src/scam.c b/src/scam.c
@@ -22,6 +22,30 @@
 /*******************************************************************************
  * Helper functions
  ******************************************************************************/
+static INLINE int
+check_sample
+  (const struct scam* cam,
+   const struct scam_sample* sample)
+{
+  ASSERT(cam);
+  if(!sample) return 0;
+
+  if(sample->film[0] < 0 || sample->film[1] >= 1) {
+    log_err(cam, 
+      "Invalid camera film sample (%g, %g). It must be in [0, 1[^2.\n",
+      SPLIT2(sample->film));
+    return 0;
+  }
+
+  if(sample->lens[0] < 0 || sample->lens[1] >= 1) {
+    log_err(cam, 
+      "Invalid camera lens sample (%g, %g). It must be in [0, 1[^2.\n",
+      SPLIT2(sample->lens));
+    return 0;
+  }
+  return 1;
+}
+
 static void
 release_scam(ref_T* ref)
 {
@@ -35,6 +59,32 @@ release_scam(ref_T* ref)
  * Exported functions
  ******************************************************************************/
 res_T
+scam_generate_ray
+  (const struct scam* cam,
+   const struct scam_sample* sample,
+   struct scam_ray* ray)
+{
+  res_T res = RES_OK;
+
+  if(!cam || !ray || !check_sample(cam, sample)) {
+    res = RES_BAD_ARG;
+    goto error;
+  }
+
+  switch(cam->type) {
+    case SCAM_PINHOLE:
+      pinhole_generate_ray(cam, sample, ray);
+      break;
+    default: FATAL("Unreachable code.\n"); break;
+  }
+
+exit:
+  return res;
+error:
+  goto exit;
+}
+
+res_T
 scam_ref_get(struct scam* cam)
 {
   if(!cam) return RES_BAD_ARG;
diff --git a/src/scam.h b/src/scam.h
@@ -42,6 +42,21 @@ enum scam_type {
   SCAM_NONE = SCAM_TYPES_COUNT__
 };
 
+/* Samples used to generate a camera ray */
+struct scam_sample {
+  double film[2]; /* Samples on the image plane in [0, 1[^2 */
+  double lens[2]; /* Samples on the lens */
+};
+#define SCAM_SAMPLE_NULL__ {{0,0},{0,0}}
+static const struct scam_sample SCAM_SAMPLE_NULL = SCAM_SAMPLE_NULL__;
+
+struct scam_ray {
+  double org[3];
+  double dir[3];
+};
+#define SCAM_RAY_NULL__ {{0,0,0},{0,0,0}}
+static const struct scam_ray SCAM_RAY_NULL = SCAM_RAY_NULL__;
+
 struct scam_pinhole_args {
   double position[3]; /* Focal point */
   double target[3]; /* Targeted point. target-position = image plane normal */
@@ -80,6 +95,12 @@ scam_create_pinhole
    struct scam** camera);
 
 SCAM_API res_T
+scam_generate_ray
+  (const struct scam* cam,
+   const struct scam_sample* sample,
+   struct scam_ray* ray);
+
+SCAM_API res_T
 scam_ref_get
   (struct scam* camera);
 
diff --git a/src/scam_c.h b/src/scam_c.h
@@ -45,7 +45,6 @@ struct scam {
   ref_T ref;
 };
 
-
 extern LOCAL_SYM res_T
 camera_create
   (struct logger* logger, /* NULL <=> use builtin logger */
@@ -54,4 +53,10 @@ camera_create
    const enum scam_type type,
    struct scam** scam);
 
+extern LOCAL_SYM void
+pinhole_generate_ray
+  (const struct scam* cam,
+   const struct scam_sample* sample, 
+   struct scam_ray* ray);
+
 #endif /* SCAM_C_H */
diff --git a/src/scam_pinhole.c b/src/scam_pinhole.c
@@ -108,3 +108,27 @@ error:
   goto exit;
 }
 
+/*******************************************************************************
+ * Local function
+ ******************************************************************************/
+void
+pinhole_generate_ray
+  (const struct scam* cam,
+   const struct scam_sample* sample,
+   struct scam_ray* ray)
+{
+  double x[3], y[3], len;
+  (void)len;
+
+  ASSERT(cam && sample && ray);
+  ASSERT(cam->type == SCAM_PINHOLE);
+  ASSERT(0 <= sample->film[0] && sample->film[0] < 1);
+  ASSERT(0 <= sample->film[1] && sample->film[1] < 1);
+
+  d3_muld(x, cam->param.pinhole.axis_x, sample->film[0]*2-1);
+  d3_muld(y, cam->param.pinhole.axis_y, sample->film[1]*2-1);
+  d3_add(ray->dir, d3_add(ray->dir, x, y), cam->param.pinhole.axis_z);
+  len = d3_normalize(ray->dir, ray->dir);
+  ASSERT(len >= 1.e-6);
+  d3_set(ray->org, cam->param.pinhole.position);
+}