demos: Add matrix math "library"
diff --git a/demos/linmath.h b/demos/linmath.h
new file mode 100644
index 0000000..4c852eb
--- /dev/null
+++ b/demos/linmath.h
@@ -0,0 +1,598 @@
+/*
+ DO WHAT THE **** YOU WANT TO PUBLIC LICENSE
+ Version 2, December 2004
+
+ Copyright (C) 2013 Wolfgang 'datenwolf' Draxinger <code@datenwolf.net>
+
+ Everyone is permitted to copy and distribute verbatim or modified
+ copies of this license document, and changing it is allowed as long
+ as the name is changed.
+
+ DO WHAT THE **** YOU WANT TO PUBLIC LICENSE
+ TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+ 0. You just DO WHAT THE FUCK YOU WANT TO.
+*/
+
+#ifndef LINMATH_H
+#define LINMATH_H
+
+#define __USE_BSD
+#include <math.h>
+
+// Converts degrees to radians.
+#define degreesToRadians(angleDegrees) (angleDegrees * M_PI / 180.0)
+
+// Converts radians to degrees.
+#define radiansToDegrees(angleRadians) (angleRadians * 180.0 / M_PI)
+
+typedef float vec3[3];
+static inline void vec3_add(vec3 r, vec3 const a, vec3 const b)
+{
+ int i;
+ for(i=0; i<3; ++i)
+ r[i] = a[i] + b[i];
+}
+static inline void vec3_sub(vec3 r, vec3 const a, vec3 const b)
+{
+ int i;
+ for(i=0; i<3; ++i)
+ r[i] = a[i] - b[i];
+}
+static inline void vec3_scale(vec3 r, vec3 const v, float const s)
+{
+ int i;
+ for(i=0; i<3; ++i)
+ r[i] = v[i] * s;
+}
+static inline float vec3_mul_inner(vec3 const a, vec3 const b)
+{
+ float p = 0.f;
+ int i;
+ for(i=0; i<3; ++i)
+ p += b[i]*a[i];
+ return p;
+}
+static inline void vec3_mul_cross(vec3 r, vec3 const a, vec3 const b)
+{
+ r[0] = a[1]*b[2] - a[2]*b[1];
+ r[1] = a[2]*b[0] - a[0]*b[2];
+ r[2] = a[0]*b[1] - a[1]*b[0];
+}
+static inline float vec3_len(vec3 const v)
+{
+ return sqrtf(vec3_mul_inner(v, v));
+}
+static inline void vec3_norm(vec3 r, vec3 const v)
+{
+ float k = 1.f / vec3_len(v);
+ vec3_scale(r, v, k);
+}
+static inline void vec3_reflect(vec3 r, vec3 const v, vec3 const n)
+{
+ float p = 2.f*vec3_mul_inner(v, n);
+ int i;
+ for(i=0;i<3;++i)
+ r[i] = v[i] - p*n[i];
+}
+
+typedef float vec4[4];
+static inline void vec4_add(vec4 r, vec4 const a, vec4 const b)
+{
+ int i;
+ for(i=0; i<4; ++i)
+ r[i] = a[i] + b[i];
+}
+static inline void vec4_sub(vec4 r, vec4 const a, vec4 const b)
+{
+ int i;
+ for(i=0; i<4; ++i)
+ r[i] = a[i] - b[i];
+}
+static inline void vec4_scale(vec4 r, vec4 v, float s)
+{
+ int i;
+ for(i=0; i<4; ++i)
+ r[i] = v[i] * s;
+}
+static inline float vec4_mul_inner(vec4 a, vec4 b)
+{
+ float p = 0.f;
+ int i;
+ for(i=0; i<4; ++i)
+ p += b[i]*a[i];
+ return p;
+}
+static inline void vec4_mul_cross(vec4 r, vec4 a, vec4 b)
+{
+ r[0] = a[1]*b[2] - a[2]*b[1];
+ r[1] = a[2]*b[0] - a[0]*b[2];
+ r[2] = a[0]*b[1] - a[1]*b[0];
+ r[3] = 1.f;
+}
+static inline float vec4_len(vec4 v)
+{
+ return sqrtf(vec4_mul_inner(v, v));
+}
+static inline void vec4_norm(vec4 r, vec4 v)
+{
+ float k = 1.f / vec4_len(v);
+ vec4_scale(r, v, k);
+}
+static inline void vec4_reflect(vec4 r, vec4 v, vec4 n)
+{
+ float p = 2.f*vec4_mul_inner(v, n);
+ int i;
+ for(i=0;i<4;++i)
+ r[i] = v[i] - p*n[i];
+}
+
+typedef vec4 mat4x4[4];
+static inline void mat4x4_identity(mat4x4 M)
+{
+ int i, j;
+ for(i=0; i<4; ++i)
+ for(j=0; j<4; ++j)
+ M[i][j] = i==j ? 1.f : 0.f;
+}
+static inline void mat4x4_dup(mat4x4 M, mat4x4 N)
+{
+ int i, j;
+ for(i=0; i<4; ++i)
+ for(j=0; j<4; ++j)
+ M[i][j] = N[i][j];
+}
+static inline void mat4x4_row(vec4 r, mat4x4 M, int i)
+{
+ int k;
+ for(k=0; k<4; ++k)
+ r[k] = M[k][i];
+}
+static inline void mat4x4_col(vec4 r, mat4x4 M, int i)
+{
+ int k;
+ for(k=0; k<4; ++k)
+ r[k] = M[i][k];
+}
+static inline void mat4x4_transpose(mat4x4 M, mat4x4 N)
+{
+ int i, j;
+ for(j=0; j<4; ++j)
+ for(i=0; i<4; ++i)
+ M[i][j] = N[j][i];
+}
+static inline void mat4x4_add(mat4x4 M, mat4x4 a, mat4x4 b)
+{
+ int i;
+ for(i=0; i<4; ++i)
+ vec4_add(M[i], a[i], b[i]);
+}
+static inline void mat4x4_sub(mat4x4 M, mat4x4 a, mat4x4 b)
+{
+ int i;
+ for(i=0; i<4; ++i)
+ vec4_sub(M[i], a[i], b[i]);
+}
+static inline void mat4x4_scale(mat4x4 M, mat4x4 a, float k)
+{
+ int i;
+ for(i=0; i<4; ++i)
+ vec4_scale(M[i], a[i], k);
+}
+static inline void mat4x4_scale_aniso(mat4x4 M, mat4x4 a, float x, float y, float z)
+{
+ int i;
+ vec4_scale(M[0], a[0], x);
+ vec4_scale(M[1], a[1], y);
+ vec4_scale(M[2], a[2], z);
+ for(i = 0; i < 4; ++i) {
+ M[3][i] = a[3][i];
+ }
+}
+static inline void mat4x4_mul(mat4x4 M, mat4x4 a, mat4x4 b)
+{
+ int k, r, c;
+ for(c=0; c<4; ++c) for(r=0; r<4; ++r) {
+ M[c][r] = 0.f;
+ for(k=0; k<4; ++k)
+ M[c][r] += a[k][r] * b[c][k];
+ }
+}
+static inline void mat4x4_mul_vec4(vec4 r, mat4x4 M, vec4 v)
+{
+ int i, j;
+ for(j=0; j<4; ++j) {
+ r[j] = 0.f;
+ for(i=0; i<4; ++i)
+ r[j] += M[i][j] * v[i];
+ }
+}
+static inline void mat4x4_translate(mat4x4 T, float x, float y, float z)
+{
+ mat4x4_identity(T);
+ T[3][0] = x;
+ T[3][1] = y;
+ T[3][2] = z;
+}
+static inline void mat4x4_translate_in_place(mat4x4 M, float x, float y, float z)
+{
+ vec4 t = {x, y, z, 0};
+ vec4 r;
+ int i;
+ for (i = 0; i < 4; ++i) {
+ mat4x4_row(r, M, i);
+ M[3][i] += vec4_mul_inner(r, t);
+ }
+}
+static inline void mat4x4_from_vec3_mul_outer(mat4x4 M, vec3 a, vec3 b)
+{
+ int i, j;
+ for(i=0; i<4; ++i) for(j=0; j<4; ++j)
+ M[i][j] = i<3 && j<3 ? a[i] * b[j] : 0.f;
+}
+static inline void mat4x4_rotate(mat4x4 R, mat4x4 M, float x, float y, float z, float angle)
+{
+ float s = sinf(angle);
+ float c = cosf(angle);
+ vec3 u = {x, y, z};
+
+ if(vec3_len(u) > 1e-4) {
+ vec3_norm(u, u);
+ mat4x4 T;
+ mat4x4_from_vec3_mul_outer(T, u, u);
+
+ mat4x4 S = {
+ { 0, u[2], -u[1], 0},
+ {-u[2], 0, u[0], 0},
+ { u[1], -u[0], 0, 0},
+ { 0, 0, 0, 0}
+ };
+ mat4x4_scale(S, S, s);
+
+ mat4x4 C;
+ mat4x4_identity(C);
+ mat4x4_sub(C, C, T);
+
+ mat4x4_scale(C, C, c);
+
+ mat4x4_add(T, T, C);
+ mat4x4_add(T, T, S);
+
+ T[3][3] = 1.;
+ mat4x4_mul(R, M, T);
+ } else {
+ mat4x4_dup(R, M);
+ }
+}
+static inline void mat4x4_rotate_X(mat4x4 Q, mat4x4 M, float angle)
+{
+ float s = sinf(angle);
+ float c = cosf(angle);
+ mat4x4 R = {
+ {1.f, 0.f, 0.f, 0.f},
+ {0.f, c, s, 0.f},
+ {0.f, -s, c, 0.f},
+ {0.f, 0.f, 0.f, 1.f}
+ };
+ mat4x4_mul(Q, M, R);
+}
+static inline void mat4x4_rotate_Y(mat4x4 Q, mat4x4 M, float angle)
+{
+ float s = sinf(angle);
+ float c = cosf(angle);
+ mat4x4 R = {
+ { c, 0.f, s, 0.f},
+ { 0.f, 1.f, 0.f, 0.f},
+ { -s, 0.f, c, 0.f},
+ { 0.f, 0.f, 0.f, 1.f}
+ };
+ mat4x4_mul(Q, M, R);
+}
+static inline void mat4x4_rotate_Z(mat4x4 Q, mat4x4 M, float angle)
+{
+ float s = sinf(angle);
+ float c = cosf(angle);
+ mat4x4 R = {
+ { c, s, 0.f, 0.f},
+ { -s, c, 0.f, 0.f},
+ { 0.f, 0.f, 1.f, 0.f},
+ { 0.f, 0.f, 0.f, 1.f}
+ };
+ mat4x4_mul(Q, M, R);
+}
+static inline void mat4x4_invert(mat4x4 T, mat4x4 M)
+{
+ float s[6];
+ float c[6];
+ s[0] = M[0][0]*M[1][1] - M[1][0]*M[0][1];
+ s[1] = M[0][0]*M[1][2] - M[1][0]*M[0][2];
+ s[2] = M[0][0]*M[1][3] - M[1][0]*M[0][3];
+ s[3] = M[0][1]*M[1][2] - M[1][1]*M[0][2];
+ s[4] = M[0][1]*M[1][3] - M[1][1]*M[0][3];
+ s[5] = M[0][2]*M[1][3] - M[1][2]*M[0][3];
+
+ c[0] = M[2][0]*M[3][1] - M[3][0]*M[2][1];
+ c[1] = M[2][0]*M[3][2] - M[3][0]*M[2][2];
+ c[2] = M[2][0]*M[3][3] - M[3][0]*M[2][3];
+ c[3] = M[2][1]*M[3][2] - M[3][1]*M[2][2];
+ c[4] = M[2][1]*M[3][3] - M[3][1]*M[2][3];
+ c[5] = M[2][2]*M[3][3] - M[3][2]*M[2][3];
+
+ /* Assumes it is invertible */
+ float idet = 1.0f/( s[0]*c[5]-s[1]*c[4]+s[2]*c[3]+s[3]*c[2]-s[4]*c[1]+s[5]*c[0] );
+
+ T[0][0] = ( M[1][1] * c[5] - M[1][2] * c[4] + M[1][3] * c[3]) * idet;
+ T[0][1] = (-M[0][1] * c[5] + M[0][2] * c[4] - M[0][3] * c[3]) * idet;
+ T[0][2] = ( M[3][1] * s[5] - M[3][2] * s[4] + M[3][3] * s[3]) * idet;
+ T[0][3] = (-M[2][1] * s[5] + M[2][2] * s[4] - M[2][3] * s[3]) * idet;
+
+ T[1][0] = (-M[1][0] * c[5] + M[1][2] * c[2] - M[1][3] * c[1]) * idet;
+ T[1][1] = ( M[0][0] * c[5] - M[0][2] * c[2] + M[0][3] * c[1]) * idet;
+ T[1][2] = (-M[3][0] * s[5] + M[3][2] * s[2] - M[3][3] * s[1]) * idet;
+ T[1][3] = ( M[2][0] * s[5] - M[2][2] * s[2] + M[2][3] * s[1]) * idet;
+
+ T[2][0] = ( M[1][0] * c[4] - M[1][1] * c[2] + M[1][3] * c[0]) * idet;
+ T[2][1] = (-M[0][0] * c[4] + M[0][1] * c[2] - M[0][3] * c[0]) * idet;
+ T[2][2] = ( M[3][0] * s[4] - M[3][1] * s[2] + M[3][3] * s[0]) * idet;
+ T[2][3] = (-M[2][0] * s[4] + M[2][1] * s[2] - M[2][3] * s[0]) * idet;
+
+ T[3][0] = (-M[1][0] * c[3] + M[1][1] * c[1] - M[1][2] * c[0]) * idet;
+ T[3][1] = ( M[0][0] * c[3] - M[0][1] * c[1] + M[0][2] * c[0]) * idet;
+ T[3][2] = (-M[3][0] * s[3] + M[3][1] * s[1] - M[3][2] * s[0]) * idet;
+ T[3][3] = ( M[2][0] * s[3] - M[2][1] * s[1] + M[2][2] * s[0]) * idet;
+}
+static inline void mat4x4_orthonormalize(mat4x4 R, mat4x4 M)
+{
+ mat4x4_dup(R, M);
+ float s = 1.;
+ vec3 h;
+
+ vec3_norm(R[2], R[2]);
+
+ s = vec3_mul_inner(R[1], R[2]);
+ vec3_scale(h, R[2], s);
+ vec3_sub(R[1], R[1], h);
+ vec3_norm(R[2], R[2]);
+
+ s = vec3_mul_inner(R[1], R[2]);
+ vec3_scale(h, R[2], s);
+ vec3_sub(R[1], R[1], h);
+ vec3_norm(R[1], R[1]);
+
+ s = vec3_mul_inner(R[0], R[1]);
+ vec3_scale(h, R[1], s);
+ vec3_sub(R[0], R[0], h);
+ vec3_norm(R[0], R[0]);
+}
+
+static inline void mat4x4_frustum(mat4x4 M, float l, float r, float b, float t, float n, float f)
+{
+ M[0][0] = 2.f*n/(r-l);
+ M[0][1] = M[0][2] = M[0][3] = 0.f;
+
+ M[1][1] = 2.*n/(t-b);
+ M[1][0] = M[1][2] = M[1][3] = 0.f;
+
+ M[2][0] = (r+l)/(r-l);
+ M[2][1] = (t+b)/(t-b);
+ M[2][2] = -(f+n)/(f-n);
+ M[2][3] = -1.f;
+
+ M[3][2] = -2.f*(f*n)/(f-n);
+ M[3][0] = M[3][1] = M[3][3] = 0.f;
+}
+static inline void mat4x4_ortho(mat4x4 M, float l, float r, float b, float t, float n, float f)
+{
+ M[0][0] = 2.f/(r-l);
+ M[0][1] = M[0][2] = M[0][3] = 0.f;
+
+ M[1][1] = 2.f/(t-b);
+ M[1][0] = M[1][2] = M[1][3] = 0.f;
+
+ M[2][2] = -2.f/(f-n);
+ M[2][0] = M[2][1] = M[2][3] = 0.f;
+
+ M[3][0] = -(r+l)/(r-l);
+ M[3][1] = -(t+b)/(t-b);
+ M[3][2] = -(f+n)/(f-n);
+ M[3][3] = 1.f;
+}
+static inline void mat4x4_perspective(mat4x4 m, float y_fov, float aspect, float n, float f)
+{
+ /* NOTE: Degrees are an unhandy unit to work with.
+ * linmath.h uses radians for everything! */
+ float const a = 1.f / tan(y_fov / 2.f);
+
+ m[0][0] = a / aspect;
+ m[0][1] = 0.f;
+ m[0][2] = 0.f;
+ m[0][3] = 0.f;
+
+ m[1][0] = 0.f;
+ m[1][1] = a;
+ m[1][2] = 0.f;
+ m[1][3] = 0.f;
+
+ m[2][0] = 0.f;
+ m[2][1] = 0.f;
+ m[2][2] = -((f + n) / (f - n));
+ m[2][3] = -1.f;
+
+ m[3][0] = 0.f;
+ m[3][1] = 0.f;
+ m[3][2] = -((2.f * f * n) / (f - n));
+ m[3][3] = 0.f;
+}
+static inline void mat4x4_look_at(mat4x4 m, vec3 eye, vec3 center, vec3 up)
+{
+ /* Adapted from Android's OpenGL Matrix.java. */
+ /* See the OpenGL GLUT documentation for gluLookAt for a description */
+ /* of the algorithm. We implement it in a straightforward way: */
+
+ /* TODO: The negation of of can be spared by swapping the order of
+ * operands in the following cross products in the right way. */
+ vec3 f;
+ vec3_sub(f, center, eye);
+ vec3_norm(f, f);
+
+ vec3 s;
+ vec3_mul_cross(s, f, up);
+ vec3_norm(s, s);
+
+ vec3 t;
+ vec3_mul_cross(t, s, f);
+
+ m[0][0] = s[0];
+ m[0][1] = t[0];
+ m[0][2] = -f[0];
+ m[0][3] = 0.f;
+
+ m[1][0] = s[1];
+ m[1][1] = t[1];
+ m[1][2] = -f[1];
+ m[1][3] = 0.f;
+
+ m[2][0] = s[2];
+ m[2][1] = t[2];
+ m[2][2] = -f[2];
+ m[2][3] = 0.f;
+
+ m[3][0] = 0.f;
+ m[3][1] = 0.f;
+ m[3][2] = 0.f;
+ m[3][3] = 1.f;
+
+ mat4x4_translate_in_place(m, -eye[0], -eye[1], -eye[2]);
+}
+
+typedef float quat[4];
+static inline void quat_identity(quat q)
+{
+ q[0] = q[1] = q[2] = 0.f;
+ q[3] = 1.f;
+}
+static inline void quat_add(quat r, quat a, quat b)
+{
+ int i;
+ for(i=0; i<4; ++i)
+ r[i] = a[i] + b[i];
+}
+static inline void quat_sub(quat r, quat a, quat b)
+{
+ int i;
+ for(i=0; i<4; ++i)
+ r[i] = a[i] - b[i];
+}
+static inline void quat_mul(quat r, quat p, quat q)
+{
+ vec3 w;
+ vec3_mul_cross(r, p, q);
+ vec3_scale(w, p, q[3]);
+ vec3_add(r, r, w);
+ vec3_scale(w, q, p[3]);
+ vec3_add(r, r, w);
+ r[3] = p[3]*q[3] - vec3_mul_inner(p, q);
+}
+static inline void quat_scale(quat r, quat v, float s)
+{
+ int i;
+ for(i=0; i<4; ++i)
+ r[i] = v[i] * s;
+}
+static inline float quat_inner_product(quat a, quat b)
+{
+ float p = 0.f;
+ int i;
+ for(i=0; i<4; ++i)
+ p += b[i]*a[i];
+ return p;
+}
+static inline void quat_conj(quat r, quat q)
+{
+ int i;
+ for(i=0; i<3; ++i)
+ r[i] = -q[i];
+ r[3] = q[3];
+}
+#define quat_norm vec4_norm
+static inline void quat_mul_vec3(vec3 r, quat q, vec3 v)
+{
+ quat v_ = {v[0], v[1], v[2], 0.f};
+
+ quat_conj(r, q);
+ quat_norm(r, r);
+ quat_mul(r, v_, r);
+ quat_mul(r, q, r);
+}
+static inline void mat4x4_from_quat(mat4x4 M, quat q)
+{
+ float a = q[3];
+ float b = q[0];
+ float c = q[1];
+ float d = q[2];
+ float a2 = a*a;
+ float b2 = b*b;
+ float c2 = c*c;
+ float d2 = d*d;
+
+ M[0][0] = a2 + b2 - c2 - d2;
+ M[0][1] = 2.f*(b*c + a*d);
+ M[0][2] = 2.f*(b*d - a*c);
+ M[0][3] = 0.f;
+
+ M[1][0] = 2*(b*c - a*d);
+ M[1][1] = a2 - b2 + c2 - d2;
+ M[1][2] = 2.f*(c*d + a*b);
+ M[1][3] = 0.f;
+
+ M[2][0] = 2.f*(b*d + a*c);
+ M[2][1] = 2.f*(c*d - a*b);
+ M[2][2] = a2 - b2 - c2 + d2;
+ M[2][3] = 0.f;
+
+ M[3][0] = M[3][1] = M[3][2] = 0.f;
+ M[3][3] = 1.f;
+}
+
+static inline void mat4x4o_mul_quat(mat4x4 R, mat4x4 M, quat q)
+{
+/* XXX: The way this is written only works for othogonal matrices. */
+/* TODO: Take care of non-orthogonal case. */
+ quat_mul_vec3(R[0], q, M[0]);
+ quat_mul_vec3(R[1], q, M[1]);
+ quat_mul_vec3(R[2], q, M[2]);
+
+ R[3][0] = R[3][1] = R[3][2] = 0.f;
+ R[3][3] = 1.f;
+}
+static inline void quat_from_mat4x4(quat q, mat4x4 M)
+{
+ float r=0.f;
+ int i;
+
+ int perm[] = { 0, 1, 2, 0, 1 };
+ int *p = perm;
+
+ for(i = 0; i<3; i++) {
+ float m = M[i][i];
+ if( m < r )
+ continue;
+ m = r;
+ p = &perm[i];
+ }
+
+ r = sqrtf(1.f + M[p[0]][p[0]] - M[p[1]][p[1]] - M[p[2]][p[2]] );
+
+ if(r < 1e-6) {
+ q[0] = 1.f;
+ q[1] = q[2] = q[3] = 0.f;
+ return;
+ }
+
+ q[0] = r/2.f;
+ q[1] = (M[p[0]][p[1]] - M[p[1]][p[0]])/(2.f*r);
+ q[2] = (M[p[2]][p[0]] - M[p[0]][p[2]])/(2.f*r);
+ q[3] = (M[p[2]][p[1]] - M[p[1]][p[2]])/(2.f*r);
+}
+
+#endif