Matrices and vectors, to make coding next commit more pleasant

includes/misc.h

@@ -71,4 +71,27 @@ void *file_load(char *fn, int *size);
 
 int cpu_check(void);
 
+// a b
+// c d
+struct matrix2d {float a,b,c,d;};
+typedef struct matrix2d matrix2d;
+
+// column vector
+struct vector2d {float x,y;};
+typedef struct vector2d vector2d;
+
+matrix2d m2d_multiply_m2d(matrix2d m1, matrix2d m2);
+vector2d m2d_multiply_v2d(matrix2d m, vector2d v);
+matrix2d m2d_multiply_float(matrix2d m, float s);
+vector2d v2d_multiply_float(vector2d v, float s);
+
+vector2d v2d_add(vector2d v1, vector2d v2);
+vector2d v2d_sub(vector2d v1, vector2d v2);
+
+matrix2d m2d_new(float me0, float me1, float me2, float me3);
+vector2d v2d_new(float x, float y);
+
+extern vector2d v2d_zero;
+extern matrix2d m2d_identity;
+
 #endif

src/misc.c

@@ -306,3 +306,68 @@ int cpu_check(void)
 #endif
 	return 0;
 }
+
+matrix2d m2d_multiply_m2d(matrix2d m1, matrix2d m2)
+{
+	matrix2d result = {
+		m1.a*m2.a+m1.b*m2.c, m1.a*m2.b+m1.b*m2.d,
+		m1.c*m2.a+m1.d*m2.c, m1.c*m2.b+m1.d*m2.d
+	};
+	return result;
+}
+vector2d m2d_multiply_v2d(matrix2d m, vector2d v)
+{
+	vector2d result = {
+		m.a*v.x+m.b*v.y,
+		m.c*v.x+m.d*v.y
+	};
+	return result;
+}
+matrix2d m2d_multiply_float(matrix2d m, float s)
+{
+	matrix2d result = {
+		m.a*s, m.b*s,
+		m.c*s, m.d*s,
+	};
+	return result;
+}
+
+vector2d v2d_multiply_float(vector2d v, float s)
+{
+	vector2d result = {
+		v.x*s,
+		v.y*s
+	};
+	return result;
+}
+
+vector2d v2d_add(vector2d v1, vector2d v2)
+{
+	vector2d result = {
+		v1.x+v2.x,
+		v1.y+v2.y
+	};
+	return result;
+}
+vector2d v2d_sub(vector2d v1, vector2d v2)
+{
+	vector2d result = {
+		v1.x-v2.x,
+		v1.y-v2.y
+	};
+	return result;
+}
+
+matrix2d m2d_new(float me0, float me1, float me2, float me3)
+{
+	matrix2d result = {me0,me1,me2,me3};
+	return result;
+}
+vector2d v2d_new(float x, float y)
+{
+	vector2d result = {x, y};
+	return result;
+}
+
+vector2d v2d_zero = {0,0};
+matrix2d m2d_identity = {1,0,0,1};