From 3935a609141623e7cfb3fa339da1a166e3917018 Mon Sep 17 00:00:00 2001
From: ladevieq <ladevie.quentin@gmail.com>
Date: Sun, 20 Dec 2020 14:49:20 +0100
Subject: Ray tracer renderer Use ray for rendering Setup basic rendering stuff
 camera / viewport

---
 src/main.cpp | 63 +++++++++++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 47 insertions(+), 16 deletions(-)

(limited to 'src/main.cpp')

diff --git a/src/main.cpp b/src/main.cpp
index 8049bac..e3b69b1 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -2,31 +2,62 @@
 
 #include "color.hpp"
 #include "vec3.hpp"
+#include "ray.hpp"
+
+color ray_color(ray& r) {
+    auto unit_dir = r.direction.unit();
+    auto t = (unit_dir.y + 1.0) * 0.5;
+
+    return (1.0 - t) * color(1.0, 1.0, 1.0) + t * color(0.5, 0.7, 1.0);
+}
 
 int main() {
-    size_t width = 256;
-    size_t height = 256;
+    // Image dimensions
+    const size_t width = 400;
+    const size_t height = width / (16.0 / 9.0);
+    // const size_t width = 256;
+    // const size_t height = 256;
 
-    // PPM format header
-    std::cout << "P3" << std::endl;
+    const double aspect_ratio = width / height;
+
+    // Viewport dimensions
+    const double viewport_width = 2.0;
+    const double viewport_height = viewport_width / aspect_ratio;
+
+    // Unit vectors for viewport pixels
+    const vec3 horizontal { viewport_width / width, 0.0, 0.0 };
+    const vec3 vertical { 0.0, viewport_height / height, 0.0 };
+    std::cerr << "Horizontal : " << horizontal << std::endl;
+    std::cerr << "Vertical : " << vertical << std::endl;
 
-    std::cout << width << std::endl;
-    std::cout << height << std::endl;
+    // We use a right handed coord system
+    const point3 eye_pos {};
+    const double focal_length = 1.0;
 
-    // Max color
-    std::cout << "255" << std::endl;
+    const point3 viewport_first_pixel =
+        horizontal * -(viewport_width / 2.0) +
+        vertical * -(viewport_height / 2.0) +
+        point3{ 0.0, 0.0, -focal_length };
+
+    const point3 first_pixel = eye_pos + viewport_first_pixel;
+
+    // PPM format header
+    std::cout << "P3\n" << width << '\n' << height << "\n 255" << std::endl;
 
     std::cerr << "Generating image" << std::endl;
 
-    for (size_t column = 0; column < width; column++) {
-        std::cerr << width - column << " lines remaining" << std::endl;
+    for (ssize_t row = height - 1; row >= 0; row--) {
+        std::cerr << height - row << " lines remaining" << std::endl;
+        for (size_t column = 0; column < width; column++) {
+            vec3 x = horizontal * column;
+            vec3 y = vertical * row;
+
+            vec3 pixel_pos = first_pixel + x + y;
+            vec3 direction = pixel_pos - eye_pos;
+
+            ray ray { eye_pos, direction };
 
-        for (size_t row = 0; row < height; row++) {
-            auto r = double(column) / (width-1);
-            auto g = double(row) / (height-1);
-            auto b = 0.25;
-            color c(r, g, b);
-            write_color(std::cout, c);
+            write_color(std::cout, ray_color(ray));
         }
     }
 
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