From 7e7ec10dea751540eda7898cf83f8471185aa063 Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@gmail.com>
Date: Thu, 16 Jul 2009 18:25:02 +0000
Subject: Add support for default textures.

---
 libdimension/dimension/scene.h | 10 ++++++++++
 libdimension/objects.c         | 18 ++++++++++++------
 libdimension/raytrace.c        | 29 +++++++++++++++++++----------
 libdimension/scene.c           |  1 +
 4 files changed, 42 insertions(+), 16 deletions(-)

diff --git a/libdimension/dimension/scene.h b/libdimension/dimension/scene.h
index aa216f4..12ad6bd 100644
--- a/libdimension/dimension/scene.h
+++ b/libdimension/dimension/scene.h
@@ -33,10 +33,20 @@ typedef enum {
 } dmnsn_quality;
 
 typedef struct {
+  /* World attributes */
   dmnsn_color background;
+  dmnsn_texture *default_texture;
+
+  /* Objects */
   dmnsn_array *objects;
+
+  /* Camera */
   dmnsn_camera *camera;
+
+  /* Canvas */
   dmnsn_canvas *canvas;
+
+  /* Rendering quality */
   dmnsn_quality quality;
 } dmnsn_scene;
 
diff --git a/libdimension/objects.c b/libdimension/objects.c
index 3c772d1..bb5a16a 100644
--- a/libdimension/objects.c
+++ b/libdimension/objects.c
@@ -120,7 +120,8 @@ dmnsn_cube_intersection_fn(const dmnsn_object *cube, dmnsn_line line)
     t_temp = (-1.0 - line.x0.x)/line.n.x;
     p = dmnsn_line_point(line, t_temp);
     if (p.y >= -1.0 && p.y <= 1.0 && p.z >= -1.0 && p.z <= 1.0
-        && t_temp >= 0.0 && (t < 0.0 || t_temp < t)) {
+        && t_temp >= 0.0 && (t < 0.0 || t_temp < t))
+    {
       t = t_temp;
     }
 
@@ -128,7 +129,8 @@ dmnsn_cube_intersection_fn(const dmnsn_object *cube, dmnsn_line line)
     t_temp = (1.0 - line.x0.x)/line.n.x;
     p = dmnsn_line_point(line, t_temp);
     if (p.y >= -1.0 && p.y <= 1.0 && p.z >= -1.0 && p.z <= 1.0
-        && t_temp >= 0.0 && (t < 0.0 || t_temp < t)) {
+        && t_temp >= 0.0 && (t < 0.0 || t_temp < t))
+    {
       t = t_temp;
     }
   }
@@ -138,7 +140,8 @@ dmnsn_cube_intersection_fn(const dmnsn_object *cube, dmnsn_line line)
     t_temp = (-1.0 - line.x0.y)/line.n.y;
     p = dmnsn_line_point(line, t_temp);
     if (p.x >= -1.0 && p.x <= 1.0 && p.z >= -1.0 && p.z <= 1.0
-        && t_temp >= 0.0 && (t < 0.0 || t_temp < t)) {
+        && t_temp >= 0.0 && (t < 0.0 || t_temp < t))
+    {
       t = t_temp;
     }
 
@@ -146,7 +149,8 @@ dmnsn_cube_intersection_fn(const dmnsn_object *cube, dmnsn_line line)
     t_temp = (1.0 - line.x0.y)/line.n.y;
     p = dmnsn_line_point(line, t_temp);
     if (p.x >= -1.0 && p.x <= 1.0 && p.z >= -1.0 && p.z <= 1.0
-        && t_temp >= 0.0 && (t < 0.0 || t_temp < t)) {
+        && t_temp >= 0.0 && (t < 0.0 || t_temp < t))
+    {
       t = t_temp;
     }
   }
@@ -156,7 +160,8 @@ dmnsn_cube_intersection_fn(const dmnsn_object *cube, dmnsn_line line)
     t_temp = (-1.0 - line.x0.z)/line.n.z;
     p = dmnsn_line_point(line, t_temp);
     if (p.x >= -1.0 && p.x <= 1.0 && p.y >= -1.0 && p.y <= 1.0
-        && t_temp >= 0.0 && (t < 0.0 || t_temp < t)) {
+        && t_temp >= 0.0 && (t < 0.0 || t_temp < t))
+    {
       t = t_temp;
     }
 
@@ -164,7 +169,8 @@ dmnsn_cube_intersection_fn(const dmnsn_object *cube, dmnsn_line line)
     t_temp = (1.0 - line.x0.z)/line.n.z;
     p = dmnsn_line_point(line, t_temp);
     if (p.x >= -1.0 && p.x <= 1.0 && p.y >= -1.0 && p.y <= 1.0
-        && t_temp >= 0.0 && (t < 0.0 || t_temp < t)) {
+        && t_temp >= 0.0 && (t < 0.0 || t_temp < t))
+    {
       t = t_temp;
     }
   }
diff --git a/libdimension/raytrace.c b/libdimension/raytrace.c
index c9217ca..470af4f 100644
--- a/libdimension/raytrace.c
+++ b/libdimension/raytrace.c
@@ -234,6 +234,8 @@ dmnsn_raytrace_shoot(dmnsn_scene *scene, dmnsn_color color, dmnsn_line ray)
   dmnsn_line ray_trans;
   dmnsn_object *object;
   dmnsn_intersection *intersection = NULL, *intersection_temp;
+  const dmnsn_texture *texture;
+  const dmnsn_pigment *pigment;
   unsigned int i;
 
   for (i = 0; i < dmnsn_array_size(scene->objects); ++i) {
@@ -245,6 +247,7 @@ dmnsn_raytrace_shoot(dmnsn_scene *scene, dmnsn_color color, dmnsn_line ray)
     /* Test for intersections with objects */
     intersection_temp = (*object->intersection_fn)(object, ray_trans);
 
+    /* Find the closest intersection to the camera */
     if (intersection_temp &&
         (!intersection || intersection_temp->t < intersection->t)) {
       dmnsn_delete_intersection(intersection);
@@ -253,23 +256,29 @@ dmnsn_raytrace_shoot(dmnsn_scene *scene, dmnsn_color color, dmnsn_line ray)
   }
 
   if (intersection) {
+    /* Default to black if we have no texture/pigment */
+    color = dmnsn_black;
+
     if (scene->quality >= DMNSN_RENDER_PIGMENT) {
-      if (intersection->texture) {
-        if (intersection->texture->pigment) {
-          color = (*intersection->texture->pigment->pigment_fn)(
-            intersection->texture->pigment,
+      /* Use the default texture if given a NULL texture */
+      texture = intersection->texture ? intersection->texture
+                                      : scene->default_texture;
+
+      if (texture) {
+        /* Use the default pigment if given a NULL pigment */
+        pigment = texture->pigment ? texture->pigment
+                                   : scene->default_texture->pigment;
+
+        if (pigment) {
+          color = (*pigment->pigment_fn)(
+            pigment,
             dmnsn_line_point(intersection->ray, intersection->t)
           );
-        } else {
-          color = dmnsn_black;
         }
-      } else {
-        color = dmnsn_black;
       }
-    } else {
-      color = dmnsn_white;
     }
 
+    /* Delete the intersection */
     dmnsn_delete_intersection(intersection);
   }
 
diff --git a/libdimension/scene.c b/libdimension/scene.c
index 7e24403..59a1eb9 100644
--- a/libdimension/scene.c
+++ b/libdimension/scene.c
@@ -27,6 +27,7 @@ dmnsn_new_scene()
 {
   dmnsn_scene *scene = malloc(sizeof(dmnsn_scene));
   if (scene) {
+    scene->default_texture = NULL;
     scene->objects = dmnsn_new_array(sizeof(dmnsn_object*));
     scene->quality = DMNSN_RENDER_FULL;
   }
-- 
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