Graphics.cpp

00001 /* 
00002  * libmbed-graphics 2D and wireframe 3D graphics library for the MBED
00003  * microcontroller platform
00004  * Copyright (C) <2009> Michael Sheldon <mike@mikeasoft.com>
00005  * Optimized and adapted for AbstractLCD interface
00006  * Copyright (C) <2010> Igor Skochinsky <skochinsky@gmail.com>
00007  *
00008  * This library is free software; you can redistribute it and/or
00009  * modify it under the terms of the GNU Library General Public
00010  * License as published by the Free Software Foundation; either
00011  * version 2 of the License, or (at your option) any later version.
00012  *
00013  * This library is distributed in the hope that it will be useful,
00014  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00015  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00016  * Library General Public License for more details.
00017  *
00018  * You should have received a copy of the GNU Library General Public
00019  * License along with this library; if not, write to the
00020  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
00021  * Boston, MA 02111-1307, USA.
00022  */
00023 
00024 #include "Graphics.h"
00025 
00026 // swap two values
00027 #define SWAP(a, b) (((a) == (b)) || (((a) ^= (b)), ((b) ^= (a)), ((a) ^= (b))))
00028 
00029 Graphics::Graphics(AbstractLCD *lcd)
00030     : _lcd(lcd) { 
00031     _cx3d = _lcd->width() / 2;
00032     _cy3d = _lcd->height() / 2;
00033     _cz3d = 150;
00034 }
00035 
00036 void Graphics::line(int x0, int y0, int x1, int y1, int colour) {
00037     // Bresenham
00038     //printf("line(%d, %d, %d, %d, %d)\n", x0, y0, x1, y1, colour);
00039     bool steep = abs(y1 - y0) > abs(x1 - x0);
00040     int temp, deltax, deltay, error, ystep, y, x;
00041     if (steep) {
00042         temp = y0;
00043         y0 = x0;
00044         x0 = temp;
00045         temp = y1;
00046         y1 = x1;
00047         x1 = temp;
00048     }
00049     if (x0 > x1) {
00050         temp = x1;
00051         x1 = x0;
00052         x0 = temp;
00053         temp = y1;
00054         y1 = y0;
00055         y0 = temp;
00056     }
00057     deltax = x1 - x0;
00058     deltay = abs(y1 - y0);
00059     error = deltax / 2;
00060     y = y0;
00061     if (y0 < y1) {
00062         ystep = 1;
00063     } else {
00064         ystep = -1;
00065     }
00066     for (x=x0; x<=x1; x++) {
00067         if (steep) {
00068             _lcd->pixel(y, x, colour);
00069         } else {
00070             _lcd->pixel(x, y, colour);
00071         }
00072         error = error - deltay;
00073         if (error < 0) {
00074             y = y + ystep;
00075             error = error + deltax;
00076         }
00077     }
00078 }
00079 
00080 void Graphics::line3d(int x0, int y0, int z0, int x1, int y1, int z1, int colour) {
00081     if (z0 + _cz3d <= 0 || z1 + _cz3d <= 0) {
00082         // Behind the camera
00083         return;
00084     }
00085     
00086     int u0 = _cx3d + x0 * _cz3d / (z0 + _cz3d);
00087     int v0 = _cy3d + y0 * _cz3d / (z0 + _cz3d);
00088     int u1 = _cx3d + x1 * _cz3d / (z1 + _cz3d);
00089     int v1 = _cy3d + y1 * _cz3d / (z1 + _cz3d);
00090     line(u0, v0, u1, v1, colour);
00091 }
00092 
00093 void Graphics::circle(int cx, int cy, int radius, int colour) {
00094     int x = 0;
00095     int y = radius;
00096     int d = 3 - (2 * radius);
00097 
00098     while (x <= y) {
00099         _lcd->pixel(cx + x, cy + y, colour);
00100         _lcd->pixel(cx + y, cy + x, colour);
00101         _lcd->pixel(cx - x, cy + y, colour);
00102         _lcd->pixel(cx + y, cy - x, colour);
00103         _lcd->pixel(cx - x, cy - y, colour);
00104         _lcd->pixel(cx - y, cy - x, colour);
00105         _lcd->pixel(cx + x, cy - y, colour);
00106         _lcd->pixel(cx - y, cy + x, colour);
00107 
00108         if (d<0)
00109             d += (4 * x) + 6;
00110         else
00111         {
00112             d += (4 * (x - y)) + 10;
00113             y--;
00114         }
00115         x++;
00116     }
00117 }