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authorTavian Barnes <tavianator@gmail.com>2009-06-18 21:39:20 +0000
committerTavian Barnes <tavianator@gmail.com>2009-06-18 21:39:20 +0000
commitc616cecfc0d91ef6ce6513c9bb43ba613103301d (patch)
tree559837c4e3d402e4ac5e8758bac18377117f0260 /libdimension
parent502658f76179e57d00da9e8756394e2ae5d930d1 (diff)
downloaddimension-c616cecfc0d91ef6ce6513c9bb43ba613103301d.tar.xz
Add performance comments to geometry.c functions.
Diffstat (limited to 'libdimension')
-rw-r--r--libdimension/geometry.c44
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;