[#5] Add triangulated mesh hittable and sample scene that showcases it

CMakeLists.txt

@@ -31,6 +31,7 @@ add_executable(ray_tracing_one_week rt_camera.c rt_colour.c rt_aabb.c rt_perlin.
                # Hittables
                hittables/rt_hittable.c hittables/rt_sphere.c hittables/rt_hittable_list.c main.c hittables/rt_moving_sphere.c
                hittables/rt_bvh.c hittables/rt_aa_rect.c hittables/rt_box.c hittables/rt_instance.c hittables/rt_const_medium.c
+               hittables/rt_triangle.c hittables/rt_triangle_mesh.c
                # Textures
                textures/rt_texture.c textures/rt_texture_solid_colour.c textures/rt_texture_checker_pattern.c
                textures/rt_texture_noise.c textures/rt_texture_image.c
@@ -39,7 +40,7 @@ add_executable(ray_tracing_one_week rt_camera.c rt_colour.c rt_aabb.c rt_perlin.
                # Random number generation
                random/rt_random.c random/rt_random.h
                # Threading
-               ${THREADING_IMPLEMENTATION} threads/rt_thread_pool.c hittables/rt_triangle.c hittables/rt_triangle.h)
+               ${THREADING_IMPLEMENTATION} threads/rt_thread_pool.c)
 
 target_compile_options(ray_tracing_one_week PRIVATE $<$<OR:$<CXX_COMPILER_ID:Clang>,$<CXX_COMPILER_ID:AppleClang>,$<CXX_COMPILER_ID:GNU>>:
                        -Wall -Wextra -Winline>

hittables/rt_hittable.h

@@ -43,4 +43,7 @@ rt_hittable_t *rt_moving_sphere_new(point3_t center_start, point3_t center_end,
 // Triangle
 rt_hittable_t *rt_triangle_new(point3_t a, point3_t b, point3_t c, rt_material_t *material);
 
+// Mesh composed of triangles
+rt_hittable_t *rt_triangle_mesh_new(const point3_t *vertices, size_t vertices_count, const size_t *triangles, size_t triangles_count, rt_material_t *material);
+
 #endif // RAY_TRACING_ONE_WEEK_RT_HITTABLE_H

hittables/rt_hittable_shared.h

@@ -23,6 +23,7 @@ typedef enum rt_hittable_type_e
     RT_HITTABLE_TYPE_INSTANCE,
     RT_HITTABLE_CONSTANT_MEDIUM,
     RT_HITTABLE_TYPE_TRIANGLE,
+    RT_HITTABLE_TYPE_MESH,
 } rt_hittable_type_t;
 
 typedef bool (*rt_hittable_hit_fn)(const rt_hittable_t *hittable, const ray_t *ray, double t_min, double t_max,

hittables/rt_triangle.c

@@ -6,7 +6,7 @@
  */
 #include <assert.h>
 #include <float.h>
-#include "rt_triangle.h"
+#include "rt_hittable.h"
 #include "rt_hittable_shared.h"
 
 typedef struct rt_triangle_s

hittables/rt_triangle_mesh.c

@@ -0,0 +1,108 @@
+/**
+ * Copyright (c) 2021, Evgeniy Morozov
+ * All rights reserved.
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+#include <assert.h>
+#include "rt_weekend.h"
+#include "rt_hittable.h"
+#include "rt_hittable_shared.h"
+#include "rt_hittable_list.h"
+
+typedef struct rt_mesh_s
+{
+    rt_hittable_t base;
+
+    rt_hittable_list_t *triangles;
+    vec3_t min, max;
+} rt_mesh_t;
+
+static rt_mesh_t rt_mesh_init(const point3_t *vertices, size_t vertices_count, const size_t *triangles, size_t triangles_count, rt_material_t *material);
+static bool rt_mesh_hit(const rt_hittable_t *hittable, const ray_t *ray, double t_min, double t_max,
+                        rt_hit_record_t *record);
+static bool rt_mesh_bb(const rt_hittable_t *hittable, double time0, double time1, rt_aabb_t *out_bb);
+static void rt_mesh_delete(rt_hittable_t *hittable);
+
+rt_hittable_t *rt_triangle_mesh_new(const point3_t *vertices, size_t vertices_count, const size_t *triangles, size_t triangles_count, rt_material_t *material)
+{
+    rt_mesh_t *mesh = (rt_mesh_t *)calloc(1, sizeof(rt_mesh_t));
+    assert(NULL != mesh);
+
+    *mesh = rt_mesh_init(vertices, vertices_count, triangles, triangles_count, material);
+    return (rt_hittable_t *)mesh;
+}
+
+static rt_mesh_t rt_mesh_init(const point3_t *vertices, size_t vertices_count, const size_t *triangles, size_t triangles_count,
+                              rt_material_t *material)
+{
+    assert(NULL != vertices);
+
+    rt_mesh_t result = {
+        .triangles = rt_hittable_list_init(triangles_count),
+        .min = vec3(0, 0, 0),
+        .max = vec3(0, 0, 0),
+    };
+    assert(NULL != triangles);
+
+    for (size_t i = 0; i < triangles_count; ++i)
+    {
+        assert(triangles[3 * i] < vertices_count);
+        point3_t a = vertices[triangles[3 * i]];
+
+        assert(triangles[3 * i + 1] < vertices_count);
+        point3_t b = vertices[triangles[3 * i + 1]];
+
+        assert(triangles[3 * i + 2] < vertices_count);
+        point3_t c = vertices[triangles[3 * i + 2]];
+
+        result.min.x = fmin(result.min.x, fmin(a.x, fmin(b.x, c.x)));
+        result.min.y = fmin(result.min.y, fmin(a.y, fmin(b.y, c.y)));
+        result.min.z = fmin(result.min.z, fmin(a.z, fmin(b.z, c.z)));
+
+        result.max.x = fmax(result.max.x, fmax(a.x, fmax(b.x, c.x)));
+        result.max.y = fmax(result.max.y, fmax(a.y, fmax(b.y, c.y)));
+        result.max.z = fmax(result.max.z, fmax(a.z, fmax(b.z, c.z)));
+
+        rt_hittable_list_add(result.triangles, rt_triangle_new(a, b, c, rt_material_claim(material)));
+    }
+
+    rt_material_delete(material);
+
+    rt_hittable_init(&result.base, RT_HITTABLE_TYPE_MESH, rt_mesh_hit, rt_mesh_bb, rt_mesh_delete);
+    return result;
+}
+
+static bool rt_mesh_hit(const rt_hittable_t *hittable, const ray_t *ray, double t_min, double t_max,
+                        rt_hit_record_t *record)
+{
+    assert(NULL != hittable);
+    assert(RT_HITTABLE_TYPE_MESH == hittable->type);
+
+    const rt_mesh_t *mesh = (const rt_mesh_t *)hittable;
+    return rt_hittable_list_hit_test(mesh->triangles, ray, t_min, t_max, record);
+}
+
+static bool rt_mesh_bb(const rt_hittable_t *hittable, double time0, double time1, rt_aabb_t *out_bb)
+{
+    assert(NULL != hittable);
+    assert(RT_HITTABLE_TYPE_MESH == hittable->type);
+
+    const rt_mesh_t *mesh = (const rt_mesh_t *)hittable;
+    *out_bb = rt_aabb(mesh->min, mesh->max);
+
+    return true;
+}
+
+static void rt_mesh_delete(rt_hittable_t *hittable)
+{
+    if (NULL == hittable)
+    {
+        return;
+    }
+    assert(RT_HITTABLE_TYPE_MESH == hittable->type);
+
+    const rt_mesh_t *mesh = (const rt_mesh_t *)hittable;
+    rt_hittable_list_deinit(mesh->triangles);
+}
+

main.c

@@ -419,7 +419,7 @@ int main(int argc, char const *argv[])
             return EXIT_FAILURE;
 
         case RT_SCENE_TRIANGLE_TEST:
-            look_from = point3(0, 0, 20);
+            look_from = point3(0, 2, 20);
             look_at = point3(0, 0, 0);
             vertical_fov = 20.0;