medfall

commit 5be7aefa548e3400592795f04b109cb55f40016c
parent 392f5e6196e2ae934d0e071517d7be5bb528eb7f
Author: Michael Savage <mikejsavage@gmail.com>
Date:   Wed Oct 12 22:53:11 +0300

Add linear_algebra.h

Diffstat:
linear_algebra.h
 | 
208
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 208 insertions(+), 0 deletions(-)
diff --git a/linear_algebra.h b/linear_algebra.h
@@ -0,0 +1,208 @@
+/*
+ * vector/matrix code
+ */
+
+#ifndef _LINEAR_ALGEBRA_H_
+#define _LINEAR_ALGEBRA_H_
+
+#include <math.h>
+
+#include "platform_inline.h"
+
+/*
+ * data definitions
+ */
+
+struct v2 {
+	union {
+		struct { float x, y; };
+		float elems[ 2 ];
+	};
+
+	v2() { }
+
+	explicit v2( float a ) {
+		x = a;
+		y = a;
+	}
+
+	explicit v2( float a, float b ) {
+		x = a;
+		y = b;
+	}
+
+	operator const GLfloat *() {
+		return elems;
+	}
+
+	v2 xx() const { return v2( x, x ); }
+	v2 xy() const { return v2( x, y ); }
+	v2 yx() const { return v2( y, x ); }
+	v2 yy() const { return v2( y, y ); }
+};
+
+struct m2 {
+	// row major 2x2 matrix
+	float a, b, c, d;
+
+	m2() { }
+
+	explicit m2( float a_, float b_, float c_, float d_ ) {
+		a = a_;
+		b = b_;
+		c = c_;
+		d = d_;
+	}
+
+	v2 row0() const { return v2( a, b ); }
+	v2 row1() const { return v2( c, d ); }
+	v2 col0() const { return v2( a, c ); }
+	v2 col1() const { return v2( b, d ); }
+};
+
+struct v3 {
+	float x, y, z;
+
+	v3() { }
+
+	explicit v3( float a ) {
+		x = a;
+		y = a;
+		z = a;
+	}
+
+	explicit v3( float a, float b, float c ) {
+		x = a;
+		y = b;
+		z = c;
+	}
+
+	explicit v3( v2 v, float c ) {
+		x = v.x;
+		y = v.y;
+		z = c;
+	}
+
+	explicit v3( float a, v2 v ) {
+		x = a;
+		y = v.x;
+		z = v.y;
+	}
+};
+
+/*
+ * v2
+ */
+
+forceinline v2 operator+( v2 lhs, v2 rhs ) {
+	return v2( lhs.x + rhs.x, lhs.y + rhs.y );
+}
+
+forceinline v2 operator-( v2 lhs, v2 rhs ) {
+	return v2( lhs.x - rhs.x, lhs.y - rhs.y );
+}
+
+forceinline v2 operator*( v2 v, float scale ) {
+	return v2( v.x * scale, v.y * scale );
+}
+
+forceinline v2 operator*( float scale, v2 v ) {
+	return v * scale;
+	return v2( v.x * scale, v.y * scale );
+}
+
+forceinline v2 operator/( v2 v, float scale ) {
+	float inv_scale = 1.0f / scale;
+	return v * inv_scale;
+}
+
+forceinline float dot( v2 lhs, v2 rhs ) {
+	return lhs.x * rhs.x + lhs.y * rhs.y;
+}
+
+/*
+ * m2
+ */
+
+forceinline m2 rot2d( float theta ) {
+	float s = sinf( theta );
+	float c = cosf( theta );
+
+	return m2( c, -s, s, c );
+}
+
+forceinline m2 m2_identity() {
+	return m2( 1, 0, 0, 1 );
+}
+
+forceinline m2 m2_scale( float scale ) {
+	return m2( scale, 0, 0, scale );
+}
+
+forceinline m2 m2_scale( float x, float y ) {
+	return m2( x, 0, 0, y );
+}
+
+forceinline m2 operator*( const m2 & lhs, const m2 & rhs ) {
+	return m2(
+		dot( lhs.row0(), rhs.col0() ), dot( lhs.row0(), rhs.col1() ),
+		dot( lhs.row1(), rhs.col0() ), dot( lhs.row1(), rhs.col1() )
+	);
+}
+
+forceinline v2 operator*( const m2 & m, v2 v ) {
+	return v2( dot( m.row0(), v ), dot( m.row1(), v ) );
+}
+
+/*
+ * v3
+ */
+
+forceinline v3 operator+( v3 lhs, v3 rhs ) {
+	return v3( lhs.x + rhs.x, lhs.y + rhs.y, lhs.z + rhs.z );
+}
+
+forceinline void operator+=( v3 & lhs, v3 rhs ) {
+	lhs.x += rhs.x;
+	lhs.y += rhs.y;
+	lhs.z += rhs.z;
+}
+
+forceinline v3 operator-( v3 lhs, v3 rhs ) {
+	return v3( lhs.x - rhs.x, lhs.y - rhs.y, lhs.z - rhs.z );
+}
+
+forceinline v3 operator*( v3 v, float scale ) {
+	return v3( v.x * scale, v.y * scale, v.z * scale );
+}
+
+forceinline v3 operator*( float scale, v3 v ) {
+	return v * scale;
+}
+
+forceinline v3 operator/( v3 v, float scale ) {
+	float inv_scale = 1.0f / scale;
+	return v * inv_scale;
+}
+
+forceinline float dot( v3 u, v3 v ) {
+	return u.x * v.x + u.y * v.y + u.z * v.z;
+}
+
+forceinline v3 cross( v3 u, v3 v ) {
+	return v3(
+		u.y * v.z - v.y * u.z,
+		v.x * u.z - u.x * v.z,
+		u.x * v.y - v.x * u.y
+	);
+}
+
+forceinline float length( v3 v ) {
+	return sqrtf( v.x * v.x + v.y * v.y + v.z * v.z );
+}
+
+forceinline v3 normalize( v3 v ) {
+	return v / length( v );
+}
+
+#endif // _LINEAR_ALGEBRA_H_