35 lines
1.1 KiB
C
35 lines
1.1 KiB
C
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#include <float.h>
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#include "clip.h"
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ClipResult clipLineToNearZ(const float* v1, const float* v2, const float dist, float* vout, float* t) {
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if(v1[2] < dist && v2[2] < dist) {
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// Both behind, no clipping
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return CLIP_RESULT_ALL_BEHIND;
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}
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if(v1[2] > dist && v2[2] > dist) {
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return CLIP_RESULT_ALL_IN_FRONT;
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}
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float vec [] = {v2[0] - v1[0], v2[1] - v1[1], v2[2] - v1[2]};
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/*
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* The plane normal will always be pointing down the negative Z so we can simplify the dot products as x and y will always be zero
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* the resulting calculation will result in simply -z of the vector
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*/
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float vecDotP = -vec[2];
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/* If the dot product is zero there is no intersection */
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if(vecDotP > FLT_MIN || vecDotP < -FLT_MIN) {
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*t = (-(dist - v1[2])) / vecDotP;
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vout[0] = v1[0] + (vec[0] * (*t));
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vout[1] = v1[1] + (vec[1] * (*t));
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vout[2] = v1[2] + (vec[2] * (*t));
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return (v1[2] >= dist) ? CLIP_RESULT_FRONT_TO_BACK : CLIP_RESULT_BACK_TO_FRONT;
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} else {
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return CLIP_RESULT_ALL_ON_PLANE;
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}
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}
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