From adb2f0d80f6146baa188770aeb678a8426892ccc Mon Sep 17 00:00:00 2001 From: Tavian Barnes Date: Tue, 16 Nov 2010 20:23:16 -0500 Subject: Make the bottom [0 0 0 1] of affine transformation matricies implicit. --- libdimension/dimension/geometry.h | 24 +++++++++--------------- 1 file changed, 9 insertions(+), 15 deletions(-) (limited to 'libdimension/dimension') diff --git a/libdimension/dimension/geometry.h b/libdimension/dimension/geometry.h index 831f48c..f5a49ec 100644 --- a/libdimension/dimension/geometry.h +++ b/libdimension/dimension/geometry.h @@ -41,9 +41,9 @@ typedef struct dmnsn_vector { /** The appropriate arguements to printf() a vector. */ #define DMNSN_VECTOR_PRINTF(v) (v).x, (v).y, (v).z -/** A 4x4 affine transformation matrix. */ +/** A 4x4 affine transformation matrix, with implied [0 0 0 1] bottom row. */ typedef struct dmnsn_matrix { - double n[4][4]; /**< The matrix elements in row-major order. */ + double n[3][4]; /**< The matrix elements in row-major order. */ } dmnsn_matrix; /** A standard format string for matricies. */ @@ -57,7 +57,7 @@ typedef struct dmnsn_matrix { (m).n[0][0], (m).n[0][1], (m).n[0][2], (m).n[0][3], \ (m).n[1][0], (m).n[1][1], (m).n[1][2], (m).n[1][3], \ (m).n[2][0], (m).n[2][1], (m).n[2][2], (m).n[2][3], \ - (m).n[3][0], (m).n[3][1], (m).n[3][2], (m).n[3][3] + 0.0, 0.0, 0.0, 1.0 /** A line, or ray. */ typedef struct dmnsn_line { @@ -145,17 +145,15 @@ dmnsn_new_vector(double x, double y, double z) return v; } -/** Construct a new matrix. */ +/** Construct a new transformation matrix. */ DMNSN_INLINE dmnsn_matrix dmnsn_new_matrix(double a0, double a1, double a2, double a3, double b0, double b1, double b2, double b3, - double c0, double c1, double c2, double c3, - double d0, double d1, double d2, double d3) + double c0, double c1, double c2, double c3) { dmnsn_matrix m = { { { a0, a1, a2, a3 }, { b0, b1, b2, b3 }, - { c0, c1, c2, c3 }, - { d0, d1, d2, d3 } } }; + { c0, c1, c2, c3 } } }; return m; } @@ -378,16 +376,12 @@ dmnsn_matrix dmnsn_matrix_mul(dmnsn_matrix lhs, dmnsn_matrix rhs); DMNSN_INLINE dmnsn_vector dmnsn_transform_vector(dmnsn_matrix T, dmnsn_vector v) { - /* 12 multiplications, 3 divisions, 12 additions */ + /* 9 multiplications, 9 additions */ dmnsn_vector r; - double w; - r.x = T.n[0][0]*v.x + T.n[0][1]*v.y + T.n[0][2]*v.z + T.n[0][3]; r.y = T.n[1][0]*v.x + T.n[1][1]*v.y + T.n[1][2]*v.z + T.n[1][3]; r.z = T.n[2][0]*v.x + T.n[2][1]*v.y + T.n[2][2]*v.z + T.n[2][3]; - w = T.n[3][0]*v.x + T.n[3][1]*v.y + T.n[3][2]*v.z + T.n[3][3]; - - return dmnsn_vector_div(r, w); + return r; } /** Transform a bounding box by a matrix. */ @@ -402,7 +396,7 @@ dmnsn_bounding_box dmnsn_transform_bounding_box(dmnsn_matrix T, DMNSN_INLINE dmnsn_line dmnsn_transform_line(dmnsn_matrix T, dmnsn_line l) { - /* 24 multiplications, 6 divisions, 30 additions */ + /* 18 multiplications, 24 additions */ dmnsn_line ret; ret.x0 = dmnsn_transform_vector(T, l.x0); ret.n = dmnsn_vector_sub( -- cgit v1.2.3