diff options
| -rw-r--r-- | libdimension/geometry.c | 44 |
1 files changed, 23 insertions, 21 deletions
diff --git a/libdimension/geometry.c b/libdimension/geometry.c index 8625e62..4f46933 100644 --- a/libdimension/geometry.c +++ b/libdimension/geometry.c @@ -77,7 +77,8 @@ dmnsn_translation_matrix(dmnsn_vector d) dmnsn_matrix dmnsn_rotation_matrix(dmnsn_vector theta) { - dmnsn_vector axis, n1, n2, n3; + /* Two trig calls, 25 multiplications, 13 additions */ + dmnsn_vector axis; double angle, s, t, x, y, z; angle = dmnsn_vector_norm(theta); @@ -86,7 +87,7 @@ dmnsn_rotation_matrix(dmnsn_vector theta) } axis = dmnsn_vector_normalize(theta); - /* Shorthand to fit logical lines on one line */ + /* Shorthand to make dmnsn_matrix_construct call legible */ s = sin(angle); t = 1.0 - cos(angle); @@ -95,29 +96,19 @@ dmnsn_rotation_matrix(dmnsn_vector theta) y = axis.y; z = axis.z; - /* Construct vectors, then a matrix, so our dmnsn_matrix_construct() call - is reasonably small */ - - n1 = dmnsn_vector_construct(1.0 + t*(x*x - 1.0), - z*s + t*x*y, - -y*s + t*x*z); - n2 = dmnsn_vector_construct(-z*s + t*x*y, - 1.0 + t*(y*y - 1.0), - x*s + t*y*z); - n3 = dmnsn_vector_construct(y*s + t*x*z, - -x*s + t*y*z, - 1.0 + t*(z*z - 1.0)); - - return dmnsn_matrix_construct(n1.x, n2.x, n3.x, 0.0, - n1.y, n2.y, n3.y, 0.0, - n1.z, n2.z, n3.z, 0.0, - 0.0, 0.0, 0.0, 1.0); + return dmnsn_matrix_construct( + 1.0 + t*(x*x - 1.0), -z*s + t*x*y, y*s + t*x*z, 0.0, + z*s + t*x*y, 1.0 + t*(y*y - 1.0), -x*s + t*y*z, 0.0, + -y*s + t*x*z, x*s + t*y*z, 1.0 + t*(z*z - 1.0), 0.0, + 0.0, 0.0, 0.0, 1.0 + ); } /* Add two vectors */ dmnsn_vector dmnsn_vector_add(dmnsn_vector lhs, dmnsn_vector rhs) { + /* 3 additions */ dmnsn_vector v = { .x = lhs.x + rhs.x, .y = lhs.y + rhs.y, .z = lhs.z + rhs.z }; @@ -128,6 +119,7 @@ dmnsn_vector_add(dmnsn_vector lhs, dmnsn_vector rhs) dmnsn_vector dmnsn_vector_sub(dmnsn_vector lhs, dmnsn_vector rhs) { + /* 3 additions */ dmnsn_vector v = { .x = lhs.x - rhs.x, .y = lhs.y - rhs.y, .z = lhs.z - rhs.z }; @@ -138,6 +130,7 @@ dmnsn_vector_sub(dmnsn_vector lhs, dmnsn_vector rhs) dmnsn_vector dmnsn_vector_mul(double lhs, dmnsn_vector rhs) { + /* 3 multiplications */ dmnsn_vector v = { .x = lhs*rhs.x, .y = lhs*rhs.y, .z = lhs*rhs.z }; return v; } @@ -146,6 +139,7 @@ dmnsn_vector_mul(double lhs, dmnsn_vector rhs) dmnsn_vector dmnsn_vector_div(dmnsn_vector lhs, double rhs) { + /* 3 divisions */ dmnsn_vector v = { .x = lhs.x/rhs, .y = lhs.y/rhs, .z = lhs.z/rhs }; return v; } @@ -154,6 +148,7 @@ dmnsn_vector_div(dmnsn_vector lhs, double rhs) double dmnsn_vector_dot(dmnsn_vector lhs, dmnsn_vector rhs) { + /* 3 multiplications, 2 additions */ return lhs.x*rhs.x + lhs.y*rhs.y + lhs.z*rhs.z; } @@ -161,6 +156,7 @@ dmnsn_vector_dot(dmnsn_vector lhs, dmnsn_vector rhs) dmnsn_vector dmnsn_vector_cross(dmnsn_vector lhs, dmnsn_vector rhs) { + /* 6 multiplications, 3 additions */ dmnsn_vector v = { .x = lhs.y*rhs.z - lhs.z*rhs.y, .y = lhs.z*rhs.x - lhs.x*rhs.z, .z = lhs.x*rhs.y - lhs.y*rhs.x }; @@ -171,6 +167,7 @@ dmnsn_vector_cross(dmnsn_vector lhs, dmnsn_vector rhs) double dmnsn_vector_norm(dmnsn_vector n) { + /* 1 sqrt, 3 multiplications, 2 additions */ return sqrt(n.x*n.x + n.y*n.y + n.z*n.z); } @@ -178,6 +175,7 @@ dmnsn_vector_norm(dmnsn_vector n) dmnsn_vector dmnsn_vector_normalize(dmnsn_vector n) { + /* 1 sqrt, 3 divisions, 3 multiplications, 2 additions */ return dmnsn_vector_div(n, dmnsn_vector_norm(n)); } @@ -349,8 +347,7 @@ dmnsn_matrix_inverse_generic(dmnsn_matrix A) static double dmnsn_matrix_cofactor(dmnsn_matrix A, unsigned int row, unsigned int col) { - /* Return the cofactor at (row, col) of matrix A. 9 multiplications, 5 - additions */ + /* 9 multiplications, 5 additions */ double n[9], C; unsigned int i, j, k = 0; @@ -376,6 +373,7 @@ dmnsn_matrix_cofactor(dmnsn_matrix A, unsigned int row, unsigned int col) dmnsn_matrix dmnsn_matrix_mul(dmnsn_matrix lhs, dmnsn_matrix rhs) { + /* 64 multiplications, 48 additions */ dmnsn_matrix r; r.n[0][0] = lhs.n[0][0]*rhs.n[0][0] + lhs.n[0][1]*rhs.n[1][0] @@ -422,6 +420,7 @@ dmnsn_matrix_mul(dmnsn_matrix lhs, dmnsn_matrix rhs) dmnsn_vector dmnsn_matrix_vector_mul(dmnsn_matrix lhs, dmnsn_vector rhs) { + /* 12 multiplications, 3 divisions, 12 additions */ dmnsn_vector r; double w; @@ -437,6 +436,7 @@ dmnsn_matrix_vector_mul(dmnsn_matrix lhs, dmnsn_vector rhs) dmnsn_line dmnsn_matrix_line_mul(dmnsn_matrix lhs, dmnsn_line rhs) { + /* 24 multiplications, 6 divisions, 30 additions */ dmnsn_line l; l.x0 = dmnsn_matrix_vector_mul(lhs, rhs.x0); l.n = dmnsn_vector_sub( @@ -450,6 +450,7 @@ dmnsn_matrix_line_mul(dmnsn_matrix lhs, dmnsn_line rhs) dmnsn_vector dmnsn_line_point(dmnsn_line l, double t) { + /* 3 multiplications, 3 additions */ return dmnsn_vector_add(l.x0, dmnsn_vector_mul(t, l.n)); } @@ -457,6 +458,7 @@ dmnsn_line_point(dmnsn_line l, double t) double dmnsn_line_index(dmnsn_line l, dmnsn_vector x) { + /* nz + 1 divisions, nz additions */ double d = 0.0; unsigned int nz = 0; |