From 5c66c6673590323b2f875b77a353cd852565b4d1 Mon Sep 17 00:00:00 2001
From: ladevieq <ladevie.quentin@gmail.com>
Date: Mon, 4 Jan 2021 22:54:07 +0100
Subject: Metallic materials

---
 include/vk-renderer.hpp | 10 +++++++++-
 shaders/compute.comp    | 22 ++++++++++++++++++----
 src/main.cpp            |  6 ++++--
 3 files changed, 31 insertions(+), 7 deletions(-)

diff --git a/include/vk-renderer.hpp b/include/vk-renderer.hpp
index 06427f0..afd5019 100644
--- a/include/vk-renderer.hpp
+++ b/include/vk-renderer.hpp
@@ -6,6 +6,11 @@
 
 #include "vec3.hpp"
 
+enum MATERIAL_TYPE: uint32_t {
+    LAMBERTIAN,
+    METAL,
+};
+
 struct input_data {
     color sky_color;
     color ground_color;
@@ -23,10 +28,13 @@ struct input_data {
         vec3 position;
         struct material {
             color albedo;
+            float fuzz;
+            uint32_t type;
+            uint32_t padding[2];
         } material;
         float radius;
         float padding[3];
-    } spheres[2];
+    } spheres[4];
 
     uint32_t max_bounce;
     float padding[3];
diff --git a/shaders/compute.comp b/shaders/compute.comp
index 6bf4205..7763538 100644
--- a/shaders/compute.comp
+++ b/shaders/compute.comp
@@ -5,6 +5,9 @@ struct ray {
 
 struct material {
     vec4 albedo;
+    float fuzz;
+    uint type;
+    uint[2] padding;
 };
 
 struct hit_info {
@@ -36,7 +39,7 @@ layout(set = 0, binding = 0) buffer Inputs {
 
     vec4[1000] random_in_sphere;
 
-    sphere[2] spheres;
+    sphere[4] spheres;
 
     uint max_bounce;
     float [3] padding;
@@ -97,7 +100,7 @@ bool hit_spheres(ray r, float min_t, float max_t, out hit_info info) {
     float closest_t = max_t;
     hit_info temp_info;
     bool hit = false;
-    for (uint sphere_index = 0; sphere_index < 2; sphere_index++) {
+    for (uint sphere_index = 0; sphere_index < 4; sphere_index++) {
         if (hit_sphere(spheres[sphere_index], r, min_t, closest_t, temp_info)) {
             info = temp_info;
             closest_t = temp_info.t;
@@ -108,7 +111,7 @@ bool hit_spheres(ray r, float min_t, float max_t, out hit_info info) {
     return hit;
 }
 
-bool lambertian_scatter(material mat, ray incident, vec2 seed, hit_info info, out vec4 attenuation, out ray scattered) {
+bool lambertian_scattering(material mat, ray incident, vec2 seed, hit_info info, out vec4 attenuation, out ray scattered) {
     vec3 unit_hemisphere_vec = to_hemisphere_vec(random_in_sphere[uint(rand(seed) * 999.0)].xyz, info.normal);
 
     attenuation = mat.albedo;
@@ -117,6 +120,16 @@ bool lambertian_scatter(material mat, ray incident, vec2 seed, hit_info info, ou
     return true;
 }
 
+bool metal_scattering(material mat, ray incident, vec2 seed, hit_info info, out vec4 attenuation, out ray scattered) {
+    vec3 reflected = reflect(normalize(incident.direction), info.normal);
+    vec3 unit_sphere_vec = random_in_sphere[uint(rand(seed) * 999.0)].xyz;
+
+    attenuation = mat.albedo;
+    scattered = ray(info.point, reflected + mat.fuzz * unit_sphere_vec); 
+
+    return (dot(scattered.direction, info.normal) > 0.0);
+}
+
 vec4 ray_color(ray r, uint sample_index) {
     hit_info info;
     uint bounces = 0;
@@ -127,7 +140,8 @@ vec4 ray_color(ray r, uint sample_index) {
         vec2 seed = vec2(info.point.x * sample_index, info.point.y * bounces) * gl_GlobalInvocationID.xy;
         ray scattered;
         vec4 attenuation;
-        if (lambertian_scatter(info.mat, current_ray, seed, info, attenuation, scattered)) {
+        if (info.mat.type == 0 && lambertian_scattering(info.mat, current_ray, seed, info, attenuation, scattered) ||
+        info.mat.type == 1 && metal_scattering(info.mat, current_ray, seed, info, attenuation, scattered)) {
             final_color *= attenuation;
             current_ray = scattered;
         } else {
diff --git a/src/main.cpp b/src/main.cpp
index 5469e13..7ba2b47 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -103,8 +103,10 @@ int main() {
         .viewport_height = 2.f,
         .proj_plane_distance = 1.f,
         .spheres = { 
-            { { 0.f, 0.f, -1.f },       { { 0.7f, 0.7f, 0.3f }, },  0.5f },
-            { { 0.f, -100.5f, -1.f },   { { 0.8f, 0.8f, 0.f }, },   100.f }
+            { { -1.f, 0.f, -1.f },      { { 0.8f, 0.8f, 0.8f }, 0.3, MATERIAL_TYPE::METAL },  0.5f },
+            { { 0.f, 0.f, -1.f },       { { 0.7f, 0.3f, 0.3f }, MATERIAL_TYPE::LAMBERTIAN },  0.5f },
+            { { 1.f, 0.f, -1.f },       { { 0.8f, 0.6f, 0.2f }, 1.0, MATERIAL_TYPE::METAL },  0.5f },
+            { { 0.f, -100.5f, -1.f },   { { 0.8f, 0.8f, 0.f }, MATERIAL_TYPE::LAMBERTIAN },   100.f }
         },
         .max_bounce = max_depth,
     };
-- 
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