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https://github.com/HarbourMasters/Starship.git
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74 lines
1.8 KiB
C
74 lines
1.8 KiB
C
#include <libultraship.h>
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void guLookAtF(float mf[4][4], float xEye, float yEye, float zEye, float xAt, float yAt, float zAt, float xUp,
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float yUp, float zUp) {
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float len;
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float xLook;
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float yLook;
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float zLook;
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float xRight;
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float yRight;
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float zRight;
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guMtxIdentF(mf);
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xLook = xAt - xEye;
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yLook = yAt - yEye;
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zLook = zAt - zEye;
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/* Negate because positive Z is behind us: */
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len = -1.0 / guSqrtf(xLook * xLook + yLook * yLook + zLook * zLook);
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xLook *= len;
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yLook *= len;
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zLook *= len;
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/* Right = Up x Look */
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xRight = yUp * zLook - zUp * yLook;
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yRight = zUp * xLook - xUp * zLook;
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zRight = xUp * yLook - yUp * xLook;
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len = 1.0 / guSqrtf(xRight * xRight + yRight * yRight + zRight * zRight);
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xRight *= len;
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yRight *= len;
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zRight *= len;
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/* Up = Look x Right */
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xUp = yLook * zRight - zLook * yRight;
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yUp = zLook * xRight - xLook * zRight;
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zUp = xLook * yRight - yLook * xRight;
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len = 1.0 / guSqrtf(xUp * xUp + yUp * yUp + zUp * zUp);
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xUp *= len;
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yUp *= len;
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zUp *= len;
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mf[0][0] = xRight;
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mf[1][0] = yRight;
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mf[2][0] = zRight;
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mf[3][0] = -(xEye * xRight + yEye * yRight + zEye * zRight);
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mf[0][1] = xUp;
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mf[1][1] = yUp;
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mf[2][1] = zUp;
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mf[3][1] = -(xEye * xUp + yEye * yUp + zEye * zUp);
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mf[0][2] = xLook;
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mf[1][2] = yLook;
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mf[2][2] = zLook;
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mf[3][2] = -(xEye * xLook + yEye * yLook + zEye * zLook);
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mf[0][3] = 0;
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mf[1][3] = 0;
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mf[2][3] = 0;
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mf[3][3] = 1;
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}
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void guLookAt(Mtx* m, float xEye, float yEye, float zEye, float xAt, float yAt, float zAt, float xUp, float yUp,
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float zUp) {
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float mf[4][4];
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guLookAtF(mf, xEye, yEye, zEye, xAt, yAt, zAt, xUp, yUp, zUp);
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guMtxF2L(mf, m);
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}
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