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display normal on sphere

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This commit is contained in:
Fabien Freling 2021-04-24 17:45:08 +02:00
parent 14c91ed8e5
commit 6a0e48a006
2 changed files with 15 additions and 9 deletions
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20
in_one_weekend/src/main.zig
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@ -16,21 +16,27 @@ const SDL_WINDOWPOS_UNDEFINED = @bitCast(c_int, sdl.c.SDL_WINDOWPOS_UNDEFINED_MA
const fps = 60; const fps = 60;
fn hitSphere(center: Point3, radius: f32, ray: Ray) bool { fn hitSphere(center: Point3, radius: f32, ray: Ray) f32 {
const ssr = ray.origin.sub(center); // Sphere-space ray, (A - C) in book const ssr = ray.origin.sub(center); // Sphere-space ray, (A - C) in book
const a = Vec3.dot(ray.direction, ray.direction); const a = Vec3.dot(ray.direction, ray.direction);
const b = 2.0 * Vec3.dot(ssr, ray.direction); const b = 2.0 * Vec3.dot(ssr, ray.direction);
const c = Vec3.dot(ssr, ssr) - (radius * radius); const c = Vec3.dot(ssr, ssr) - (radius * radius);
const discriminant = b * b - 4 * a * c; const discriminant = b * b - 4 * a * c;
return discriminant > 0; if (discriminant < 0) {
return -1;
} else {
return (-b - std.math.sqrt(discriminant)) / (2 * a);
}
} }
fn rayColor(ray: Ray) Color { fn rayColor(ray: Ray) Color {
if (hitSphere(Point3{ .x = 0, .y = 0, .z = -1 }, 0.5, ray)) { var t = hitSphere(Point3{ .x = 0, .y = 0, .z = -1 }, 0.5, ray);
return Color{ .x = 1, .y = 0, .z = 0 }; if (t > 0) {
const normal = vec3.unitVector(ray.at(t).sub(Vec3{ .z = -1 }));
return normal.add(Vec3{ .x = 1, .y = 1, .z = 1}).div(2);
} }
const unitDirection = vec3.unitVector(ray.direction); const unitDirection = vec3.unitVector(ray.direction);
const t = 0.5 * (unitDirection.y + 1.0); t = 0.5 * (unitDirection.y + 1.0);
const white = Color{ .x = 1.0, .y = 1.0, .z = 1.0 }; const white = Color{ .x = 1.0, .y = 1.0, .z = 1.0 };
const blue = Color{ .x = 0.5, .y = 0.7, .z = 1.0 }; const blue = Color{ .x = 0.5, .y = 0.7, .z = 1.0 };
return white.mul(1.0 - t).add(blue.mul(t)); return white.mul(1.0 - t).add(blue.mul(t));
@ -45,7 +51,7 @@ pub fn main() anyerror!void {
// Image // Image
const aspectRatio: f32 = 16.0 / 9.0; const aspectRatio: f32 = 16.0 / 9.0;
const imageWidth = 400; const imageWidth = 600;
const imageHeight = @floatToInt(usize, imageWidth / aspectRatio); const imageHeight = @floatToInt(usize, imageWidth / aspectRatio);
// Camera // Camera
@ -87,7 +93,7 @@ pub fn main() anyerror!void {
const v = @intToFloat(f32, (imageHeight - 1) - j) / @intToFloat(f32, (imageHeight - 1)); const v = @intToFloat(f32, (imageHeight - 1) - j) / @intToFloat(f32, (imageHeight - 1));
const r = Ray{ const r = Ray{
.origin = origin, .origin = origin,
.direction = lowerLeftCorner.add(horizontal.mul(u).add(vertical.mul(v).sub(origin))), .direction = lowerLeftCorner.add(horizontal.mul(u)).add(vertical.mul(v)).sub(origin),
}; };
const pixelColor = rayColor(r); const pixelColor = rayColor(r);
sdl.setSurfacePixel(surface, i, j, pixelColor); sdl.setSurfacePixel(surface, i, j, pixelColor);

4
in_one_weekend/src/ray.zig
View file

@ -5,7 +5,7 @@ pub const Ray = struct {
origin: Point3, origin: Point3,
direction: Vec3, direction: Vec3,
pub fn at(t: f32) Point3 { pub fn at(self: Ray, t: f32) Point3 {
return origin.add(direction.mul(t)); return self.origin.add(self.direction.mul(t));
} }
}; };