23 lines
856 B
C++
23 lines
856 B
C++
#include "viewing_ray.h"
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void viewing_ray(
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const Camera &camera,
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const int i,
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const int j,
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const int width,
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const int height,
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Ray &ray) {
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/* Based on
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* Fundamentals in Computer Graphics - Fourth Edition, Chapter 4.3.2 Perspective views.
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* Steve Marschner & Peter Shirley
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*/
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/* Determine the direction of the ray, using the camera and pixel location. */
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double u = 0 - camera.width / 2 + camera.width * (j + 0.5) / width;
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double v = 0 - camera.height / 2 + camera.height * (i + 0.5) / height;
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ray.origin = camera.e;
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/* NOTE I flipped the vertical axis of the pixels, because in computer graphics we assume the bottom left pixel
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* is (0,0), while traditional jpg assumes (0,0) to be the upper left pixel. */
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ray.direction = (0 - camera.d) * camera.w + u * camera.u - v * camera.v;
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}
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