/* brushlib - The MyPaint Brush Library
* Copyright (C) 2007-2008 Martin Renold <martinxyz@gmx.ch>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#ifndef __MAPPING_H__
#define __MAPPING_H__
// user-defined mappings
// (the curves you can edit in the brush settings)
namespace brushlib {
class Mapping {
private:
typedef struct {
// a set of control points (stepwise linear)
float xvalues[8];
float yvalues[8];
int n;
} ControlPoints;
int inputs;
ControlPoints * pointsList; // one for each input
int inputs_used; // optimization
public:
float base_value;
Mapping(int inputs_) {
inputs = inputs_;
pointsList = new ControlPoints[inputs];
for (int i=0; i<inputs; i++) pointsList[i].n = 0;
inputs_used = 0;
base_value = 0;
}
~Mapping() {
delete [] pointsList;
}
void set_n (int input, int n)
{
assert (input >= 0 && input < inputs);
assert (n >= 0 && n <= 8);
assert (n != 1); // cannot build a linear mapping with only one point
ControlPoints * p = pointsList + input;
if (n != 0 && p->n == 0) inputs_used++;
if (n == 0 && p->n != 0) inputs_used--;
assert(inputs_used >= 0);
assert(inputs_used <= inputs);
p->n = n;
}
void set_point (int input, int index, float x, float y)
{
assert (input >= 0 && input < inputs);
assert (index >= 0 && index < 8);
ControlPoints * p = pointsList + input;
assert (index < p->n);
if (index > 0) {
assert (x >= p->xvalues[index-1]);
}
p->xvalues[index] = x;
p->yvalues[index] = y;
}
bool is_constant()
{
return inputs_used == 0;
}
float calculate (float * data)
{
int j;
float result;
result = base_value;
// constant mapping (common case)
if (inputs_used == 0) return result;
for (j=0; j<inputs; j++) {
ControlPoints * p = pointsList + j;
if (p->n) {
float x, y;
x = data[j];
// find the segment with the slope that we need to use
float x0, y0, x1, y1;
x0 = p->xvalues[0];
y0 = p->yvalues[0];
x1 = p->xvalues[1];
y1 = p->yvalues[1];
int i;
for (i=2; i<p->n && x>x1; i++) {
x0 = x1;
y0 = y1;
x1 = p->xvalues[i];
y1 = p->yvalues[i];
}
if (x0 == x1) {
y = y0;
} else {
// linear interpolation
y = (y1*(x - x0) + y0*(x1 - x)) / (x1 - x0);
}
result += y;
}
}
return result;
}
// used in python for the global pressure mapping
float calculate_single_input (float input)
{
assert(inputs == 1);
return calculate(&input);
}
};
}
#endif