276 lines
7.0 KiB
C++
276 lines
7.0 KiB
C++
//
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// Portable drawing routines for the Fast Light Tool Kit (FLTK).
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//
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// Copyright 1998-2016 by Bill Spitzak and others.
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//
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// This library is free software. Distribution and use rights are outlined in
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// the file "COPYING" which should have been included with this file. If this
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// file is missing or damaged, see the license at:
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//
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// https://www.fltk.org/COPYING.php
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//
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// Please see the following page on how to report bugs and issues:
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//
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// https://www.fltk.org/bugs.php
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//
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/**
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\file Fl_OpenGL_Graphics_Driver_vertex.cxx
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\brief Portable drawing code for drawing arbitrary shapes with
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simple 2D transformations, implemented for OpenGL.
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*/
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#include "Fl_OpenGL_Graphics_Driver.H"
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#include <FL/fl_draw.H>
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#include <FL/gl.h>
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#include <FL/math.h>
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#include <stdlib.h>
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// OpenGL does not support rednering non-convex polygons. Calling
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// glBegin(GL_POLYGON); witha complex outline will create rather random
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// errors, often overwrinting gaps and holes.
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//
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// Defining SLOW_COMPLEX_POLY will activate a line-by-line drawing method
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// for complex polygons that is correct for FLTK, but also a lot slower.
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//
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// It's recommended that SLOW_COMPLEX_POLY is defined, but fl_begin_polygon()
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// is used instead of fl_begin_complex_polygon() whenever possible.
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//#undef SLOW_COMPLEX_POLY
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#define SLOW_COMPLEX_POLY
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#ifdef SLOW_COMPLEX_POLY
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# define GAP (1e9f)
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#endif
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// Event though there are faster versions of the functions in OpenGL,
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// we use the default FLTK implementation for compatibility in the
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// following functions.
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// void Fl_OpenGL_Graphics_Driver::push_matrix()
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// void Fl_OpenGL_Graphics_Driver::pop_matrix()
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// void Fl_OpenGL_Graphics_Driver::mult_matrix(double a, double b, double c, double d, double x, double y)
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// void Fl_OpenGL_Graphics_Driver::rotate(double d)
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// double Fl_OpenGL_Graphics_Driver::transform_x(double x, double y)
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// double Fl_OpenGL_Graphics_Driver::transform_y(double x, double y)
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// double Fl_OpenGL_Graphics_Driver::transform_dx(double x, double y)
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// double Fl_OpenGL_Graphics_Driver::transform_dy(double x, double y)
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void Fl_OpenGL_Graphics_Driver::begin_points() {
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n = 0; gap_ = 0;
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what = POINTS;
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glBegin(GL_POINTS);
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}
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void Fl_OpenGL_Graphics_Driver::end_points() {
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glEnd();
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}
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void Fl_OpenGL_Graphics_Driver::begin_line() {
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n = 0; gap_ = 0;
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what = LINE;
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glBegin(GL_LINE_STRIP);
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}
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void Fl_OpenGL_Graphics_Driver::end_line() {
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glEnd();
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}
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void Fl_OpenGL_Graphics_Driver::begin_loop() {
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n = 0; gap_ = 0;
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what = LOOP;
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glBegin(GL_LINE_LOOP);
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}
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void Fl_OpenGL_Graphics_Driver::end_loop() {
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glEnd();
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}
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void Fl_OpenGL_Graphics_Driver::begin_polygon() {
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n = 0; gap_ = 0;
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what = POLYGON;
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glBegin(GL_POLYGON);
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}
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void Fl_OpenGL_Graphics_Driver::end_polygon() {
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glEnd();
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}
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void Fl_OpenGL_Graphics_Driver::begin_complex_polygon() {
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n = 0;
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what = COMPLEX_POLYGON;
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#ifndef SLOW_COMPLEX_POLY
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glBegin(GL_POLYGON);
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#endif
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}
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void Fl_OpenGL_Graphics_Driver::gap() {
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#ifdef SLOW_COMPLEX_POLY
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// drop gaps at the start or gap after gap
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if (n==0 || n==gap_) // || pnVertex==pVertexGapStart)
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return;
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// create a loop
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XPOINT& p = xpoint[gap_];
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transformed_vertex(p.x, p.y);
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transformed_vertex(GAP, 0.0);
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gap_ = n;
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#else
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glEnd();
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glBegin(GL_POLYGON);
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#endif
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}
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#ifdef SLOW_COMPLEX_POLY
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// Draw a complex polygon line by line from the top to the bottom.
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void Fl_OpenGL_Graphics_Driver::end_complex_polygon()
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{
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int i, y;
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XPOINT *v0, *v1;
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// don't bother if no polygon is defined
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if (n < 2) return;
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// make sure that we always have a closed loop by appending the first
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// coordinate again as the alst coordinate
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gap();
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// find the bounding box for this polygon
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v0 = xpoint;
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v0->y -= 0.1f;
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float xMin = v0->x, xMax = xMin;
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int yMin = (int)v0->y, yMax = yMin;
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for (i = 1; i < n; i++) {
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v0++;
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v0->y -= 0.1f;
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float v0x = v0->x;
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int v0y = (int)v0->y;
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if (v0x == GAP) continue;
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if (v0x <= xMin) xMin = v0x;
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if (v0x >= xMax) xMax = v0x;
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if (v0y <= yMin) yMin = v0y;
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if (v0y >= yMax) yMax = v0y;
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}
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int nNodes;
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float *nodeX = (float*)malloc((n-1)*sizeof(float)), swap;
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if (!nodeX)
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return;
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// loop through the rows of the image
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for (y = yMin; y <= yMax; y++) {
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// Build a list of all crossing points with this y axis
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v0 = xpoint + 0;
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v1 = xpoint + 1;
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nNodes = 0;
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for (i = 1; i < n; i++) {
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if (v1->x==GAP) { // skip the gap
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i++; v0++; v1++; v0++; v1++;
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continue;
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}
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if ( (v1->y < y && v0->y >= y)
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|| (v0->y < y && v1->y >= y) )
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{
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float dy = v0->y - v1->y;
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if (fabsf(dy)>.0001f) {
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nodeX[nNodes++] = v1->x + ((y - v1->y) / dy) * (v0->x - v1->x);
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} else {
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nodeX[nNodes++] = v1->x;
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}
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}
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v0++; v1++;
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}
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// sort the nodes, via a simple Bubble sort
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i = 0;
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while (i < nNodes-1) {
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if (nodeX[i] > nodeX[i+1]) {
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swap = nodeX[i];
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nodeX[i] = nodeX[i+1];
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nodeX[i+1] = swap;
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if (i) i--;
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} else {
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i++;
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}
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}
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// fill the pixels between node pairs
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// Using lines requires additional attention to the current line width and pattern
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// We are using glRectf instead
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// glBegin(GL_LINES);
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for (i = 0; i < nNodes; i += 2) {
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float x0 = nodeX[i];
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if (x0 >= xMax)
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break;
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float x1 = nodeX[i+1];
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if (x1 > xMin) {
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if (x0 < xMin)
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x0 = xMin;
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if (x1 > xMax)
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x1 = xMax;
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glRectf((GLfloat)(x0-0.25f), (GLfloat)(y), (GLfloat)(x1+0.25f), (GLfloat)(y+1.0f));
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// glVertex2f((GLfloat)x0, (GLfloat)y);
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// glVertex2f((GLfloat)x1, (GLfloat)y);
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}
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}
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// glEnd();
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}
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::free(nodeX);
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}
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#else
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// FXIME: non-convex polygons are not supported yet
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// use gluTess* functions to do this; search for gluBeginPolygon
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void Fl_OpenGL_Graphics_Driver::end_complex_polygon() {
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glEnd();
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}
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#endif
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// remove equal points from closed path
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void Fl_OpenGL_Graphics_Driver::fixloop() { }
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void Fl_OpenGL_Graphics_Driver::transformed_vertex(double xf, double yf) {
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#ifdef SLOW_COMPLEX_POLY
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if (what==COMPLEX_POLYGON) {
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Fl_Graphics_Driver::transformed_vertex(xf, yf);
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} else {
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glVertex2d(xf, yf);
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}
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#else
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glVertex2d(xf, yf);
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#endif
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}
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void Fl_OpenGL_Graphics_Driver::circle(double cx, double cy, double r) {
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double rx = r * (m.c ? sqrt(m.a*m.a+m.c*m.c) : fabs(m.a));
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double ry = r * (m.b ? sqrt(m.b*m.b+m.d*m.d) : fabs(m.d));
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double rMax;
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if (ry>rx) rMax = ry; else rMax = rx;
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// from http://slabode.exofire.net/circle_draw.shtml and many other places
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int num_segments = (int)(10 * sqrt(rMax))+1;
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double theta = 2 * M_PI / float(num_segments);
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double tangetial_factor = tan(theta);
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double radial_factor = cos(theta);//calculate the radial factor
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double x = r; //we start at angle = 0
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double y = 0;
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glBegin(GL_LINE_LOOP);
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for(int ii = 0; ii < num_segments; ii++) {
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vertex(x + cx, y + cy); // output vertex
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double tx = -y;
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double ty = x;
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x += tx * tangetial_factor;
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y += ty * tangetial_factor;
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x *= radial_factor;
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y *= radial_factor;
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}
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glEnd();
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}
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