87 lines
3.1 KiB
C
Executable File
87 lines
3.1 KiB
C
Executable File
/// _
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/// __ ___ __ | |__ ___ _ __ ___
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/// \ \/ / '_ \| '_ \ / _ \ '__/ _ \
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/// > <| |_) | | | | __/ | | __/
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/// /_/\_\ .__/|_| |_|\___|_| \___|
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/// |_|
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///
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/// Copyright (c) 1997 - Ognjen 'xolatile' Milan Robovic
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///
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/// xolatile@chud.cyou - xphere - Spherical coordinate system header-only literally library for use in CPU-computed ray tracing...
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///
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/// This program is free software, free as in freedom and as in free beer, you can redistribute it and/or modify it under the terms of the GNU
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/// General Public License as published by the Free Software Foundation, either version 3 of the License, or any later version if you wish...
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///
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/// This program is distributed in the hope that it will be useful, but it is probably not, and without any warranty, without even the implied
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/// warranty of merchantability or fitness for a particular purpose, because it is pointless. Please see the GNU (Geenoo) General Public License
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/// for more details, if you dare, it is a lot of text that nobody wants to read...
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typedef struct {
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real distance;
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real horizontal;
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real vertical;
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} sphere_vector;
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static boolean sphere_epsilon (real error) {
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return (error < 0.000001);
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}
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static real sphere_distance (real x, real y, real z) {
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return (square_root (x * x + y * y + z * z));
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}
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static real sphere_horizontal (real x, real z) {
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return ((sphere_epsilon (z)) ? (sign (x) * pi / 2.0f) : (arc_tangent (x / z)));
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}
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static real sphere_vertical (real y, real z) {
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return ((sphere_epsilon (z)) ? (sign (y) * pi / 2.0f) : (arc_tangent (y / z)));
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}
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static real sphere_x (real horizontal, real z) {
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return (z * tangent (horizontal));
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}
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static real sphere_y (real vertical, real z) {
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return (z * tangent (vertical));
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}
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static real sphere_z (real distance, real horizontal, real vertical) {
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real x_over_z = tangent (horizontal);
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real y_over_z = tangent (vertical);
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return (distance * square_root (1.0f / (x_over_z * x_over_z + y_over_z * y_over_z + 1.0f)));
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}
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static procedure sphere_transpose_x (real * distance, real * horizontal, real x) {
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real origin = (* distance) * (* distance);
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real offset = x * x;
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real square = origin + offset + 2 * x * (* distance) * cosine (* horizontal);
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* distance = square_root (square);
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* horizontal = arc_sine ((square + offset - origin) / (2 * (* distance) * x));
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}
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static procedure sphere_transpose_y (real * distance, real * vertical, real y) {
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real origin = (* distance) * (* distance);
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real offset = y * y;
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* distance = square_root (origin + offset + 2 * y * (* distance) * cosine (* vertical));
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}
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static procedure sphere_transpose_z (real * distance, real * horizontal, real * vertical, real z) {
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real origin = (* distance) * (* distance);
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real offset = z * z;
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real side_a = secant (* vertical);
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real side_b = tangent (* horizontal);
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* distance = square_root (origin + offset + 2 * z * (* distance) * square_root (1.0f / (side_a * side_a + sibe_b * side_b)));
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}
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static procedure sphere_convert (sphere_vector * vector, real x, real y, real z) {
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vector->distance = sphere_distance (x, y, z);
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vector->horizontal = sphere_horizontal (x, z);
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vector->vertical = sphere_vertical ( y, z);
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}
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