From 71e4f3812982dba2efb471283d310224e8db363e Mon Sep 17 00:00:00 2001 From: "Kartik K. Agaram" Date: Wed, 3 Mar 2021 22:09:50 -0800 Subject: 7842 - new directory organization Baremetal is now the default build target and therefore has its sources at the top-level. Baremetal programs build using the phase-2 Mu toolchain that requires a Linux kernel. This phase-2 codebase which used to be at the top-level is now under the linux/ directory. Finally, the phase-2 toolchain, while self-hosting, has a way to bootstrap from a C implementation, which is now stored in linux/bootstrap. The bootstrap C implementation uses some literate programming tools that are now in linux/bootstrap/tools. So the whole thing has gotten inverted. Each directory should build one artifact and include the main sources (along with standard library). Tools used for building it are relegated to sub-directories, even though those tools are often useful in their own right, and have had lots of interesting programs written using them. A couple of things have gotten dropped in this process: - I had old ways to run on just a Linux kernel, or with a Soso kernel. No more. - I had some old tooling for running a single test at the cursor. I haven't used that lately. Maybe I'll bring it back one day. The reorg isn't done yet. Still to do: - redo documentation everywhere. All the README files, all other markdown, particularly vocabulary.md. - clean up how-to-run comments at the start of programs everywhere - rethink what to do with the html/ directory. Do we even want to keep supporting it? In spite of these shortcomings, all the scripts at the top-level, linux/ and linux/bootstrap are working. The names of the scripts also feel reasonable. This is a good milestone to take stock at. --- linux/raytracing/main.cc | 112 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 112 insertions(+) create mode 100644 linux/raytracing/main.cc (limited to 'linux/raytracing/main.cc') diff --git a/linux/raytracing/main.cc b/linux/raytracing/main.cc new file mode 100644 index 00000000..35177279 --- /dev/null +++ b/linux/raytracing/main.cc @@ -0,0 +1,112 @@ +#include + +// print float in some sort of intuitive hex that also helps visualize the underlying bits +void p(std::ostream &out, float f) { + int bits = *(int*)&f; + // sign + if (bits & 0x80000000) { + out << '-'; + } + // mantissa + int mantissa = bits & 0x007fffff; + int exponent = (bits & 0x7f800000) >> 23; + out << std::hex << mantissa << "P" << std::dec << (exponent-127); +} + +#include "color.h" +#include "ray.h" +#include "vec3.h" + +color ray_color(const ray& r) { +//? std::cerr << "r.dir: " << r.direction() << '\n'; +//? std::cerr << "r.dir length: "; +//? p(std::cerr, r.direction().length()); +//? std::cerr << '\n'; + vec3 unit_direction = unit_vector(r.direction()); +//? std::cerr << "r.dir normalized: " << unit_direction << '\n'; + float t = 0.5*(unit_direction.y() + 1.0); +//? std::cerr << "t: "; +//? p(std::cerr, t); +//? std::cerr << '\n'; + vec3 whitening = (1.0-t)*color(1.0, 1.0, 1.0); +//? std::cerr << "whitening: "; +//? p(std::cerr, whitening.x()); +//? std::cerr << " "; +//? p(std::cerr, whitening.y()); +//? std::cerr << " "; +//? p(std::cerr, whitening.z()); +//? std::cerr << "\n"; + vec3 base = t*color(0.5, 0.7, 1.0); +//? std::cerr << "base: "; +//? p(std::cerr, base.x()); +//? std::cerr << " "; +//? p(std::cerr, base.y()); +//? std::cerr << " "; +//? p(std::cerr, base.z()); +//? std::cerr << "\n"; + vec3 result = base + whitening; +//? std::cerr << "result: "; +//? p(std::cerr, result.x()); +//? std::cerr << " "; +//? p(std::cerr, result.y()); +//? std::cerr << " "; +//? p(std::cerr, result.z()); +//? std::cerr << "\n"; + return result; +} + +int main() { + + // Image + const float aspect_ratio = 16.0 / 9.0; +//? std::cerr << "aspect ratio: " << aspect_ratio << ' ' << std::hex << *(int*)&aspect_ratio << '\n'; + const int image_width = 400; + const int image_height = static_cast(image_width / aspect_ratio); + + // Camera + + float viewport_height = 2.0; +//? std::cerr << "viewport height: " << viewport_height << ' ' << std::hex << *(int*)&viewport_height << '\n'; + float viewport_width = aspect_ratio * viewport_height; +//? std::cerr << "viewport width: " << viewport_width << ' ' << std::hex << *(int*)&viewport_width << '\n'; + float focal_length = 1.0; + + auto origin = point3(0, 0, 0); + auto horizontal = vec3(viewport_width, 0, 0); + auto vertical = vec3(0, viewport_height, 0); + auto lower_left_corner = origin - horizontal/2 - vertical/2 - vec3(0, 0, focal_length); + + // Render + + std::cout << "P3\n" << image_width << " " << image_height << "\n255\n"; + + for (int j = image_height-1; j >= 0; --j) { +//? std::cerr << "\rScanlines remaining: " << j << ' ' << std::flush; + for (int i = 0; i < image_width; ++i) { + auto u = float(i) / (image_width-1); +//? std::cerr << "u: " << u << '\n'; + auto v = float(j) / (image_height-1); + ray r(origin, lower_left_corner + u*horizontal + v*vertical - origin); +//? std::cerr << "ray origin: " << r.orig.x() << " " << r.orig.y() << " " << r.orig.z() << '\n'; +//? std::cerr << "ray direction: " << r.dir.x() << " " << r.dir.y() << " " << r.dir.z() << '\n'; +//? std::cerr << "ray dir.x: " << r.dir.x() << " "; +//? p(std::cerr, r.dir.x()); +//? std::cerr << '\n'; + color pixel_color = ray_color(r); +//? std::cerr << "pixel color: " << pixel_color.x() << " " << pixel_color.y() << " " << pixel_color.z() << '\n'; + +//? std::cout << "("; +//? p(std::cout, pixel_color.x()); +//? std::cout << ", "; +//? p(std::cout, pixel_color.y()); +//? std::cout << ", "; +//? p(std::cout, pixel_color.z()); +//? std::cout << ")\n"; + write_color(std::cout, pixel_color); +//? break; + } +//? break; + } + +//? std::cerr << "\r"; +} -- cgit 1.4.1-2-gfad0