1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/main.cc	Sat Jan 24 16:36:34 2015 +0200
     1.3 @@ -0,0 +1,219 @@
     1.4 +#include <stdio.h>
     1.5 +#include <stdlib.h>
     1.6 +#include <stdarg.h>
     1.7 +#include <assert.h>
     1.8 +#include <GL/glut.h>
     1.9 +#include <vmath/vmath.h>
    1.10 +#include <drawtext.h>
    1.11 +
    1.12 +bool init();
    1.13 +void display();
    1.14 +void draw_grid();
    1.15 +void draw_label(const Vector2 &pos, const char *fmt, ...);
    1.16 +void reshape(int x, int y);
    1.17 +void keyb(unsigned char key, int x, int y);
    1.18 +void keyb_up(unsigned char key, int x, int y);
    1.19 +void mouse(int bn, int st, int x, int y);
    1.20 +void motion(int x, int y);
    1.21 +Vector2 screen_to_world(int x, int y);
    1.22 +
    1.23 +int win_xsz, win_ysz;
    1.24 +float aspect;
    1.25 +
    1.26 +Matrix4x4 proj;
    1.27 +Vector2 cur_point;
    1.28 +bool cur_point_valid;
    1.29 +
    1.30 +bool keystate[256];
    1.31 +dtx_font *font;
    1.32 +float pan[2], zoom = 1.0;
    1.33 +
    1.34 +int main(int argc, char **argv)
    1.35 +{
    1.36 +	glutInit(&argc, argv);
    1.37 +	glutInitWindowSize(1024, 768);
    1.38 +	glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_MULTISAMPLE);
    1.39 +	glutCreateWindow("Interactive projection diagram");
    1.40 +
    1.41 +	glutDisplayFunc(display);
    1.42 +	glutReshapeFunc(reshape);
    1.43 +	glutKeyboardFunc(keyb);
    1.44 +	glutKeyboardUpFunc(keyb_up);
    1.45 +	glutMouseFunc(mouse);
    1.46 +	glutMotionFunc(motion);
    1.47 +
    1.48 +	if(!init()) {
    1.49 +		return 1;
    1.50 +	}
    1.51 +
    1.52 +	glutMainLoop();
    1.53 +	return 0;
    1.54 +}
    1.55 +
    1.56 +bool init()
    1.57 +{
    1.58 +	if(!(font = dtx_open_font("data/font.ttf", 16))) {
    1.59 +		fprintf(stderr, "failed to open font\n");
    1.60 +		return false;
    1.61 +	}
    1.62 +
    1.63 +	glEnable(GL_MULTISAMPLE);
    1.64 +	proj.set_perspective(DEG_TO_RAD(60), 1, 0.5, 500.0);
    1.65 +	return true;
    1.66 +}
    1.67 +
    1.68 +void display()
    1.69 +{
    1.70 +	glClear(GL_COLOR_BUFFER_BIT);
    1.71 +
    1.72 +	glMatrixMode(GL_MODELVIEW);
    1.73 +	glLoadIdentity();
    1.74 +	glTranslatef(-pan[0], -pan[1], 0);
    1.75 +	glScalef(zoom, zoom, zoom);
    1.76 +
    1.77 +	draw_grid();
    1.78 +
    1.79 +	if(cur_point_valid) {
    1.80 +		glPointSize(7.0);
    1.81 +		glBegin(GL_POINTS);
    1.82 +		glColor3f(0.2, 1, 0.2);
    1.83 +		glVertex2f(cur_point.x, cur_point.y);
    1.84 +		glEnd();
    1.85 +
    1.86 +		glColor3f(0.15, 0.5, 0.15);
    1.87 +		draw_label(cur_point, "(%.2f, %.2f)", cur_point.x, cur_point.y);
    1.88 +	}
    1.89 +
    1.90 +	glutSwapBuffers();
    1.91 +	assert(glGetError() == GL_NO_ERROR);
    1.92 +}
    1.93 +
    1.94 +#define LINE(x0, y0, x1, y1)	(glVertex2f(x0, y0), glVertex2f(x1, y1))
    1.95 +
    1.96 +void draw_grid()
    1.97 +{
    1.98 +	float ymin = -1;
    1.99 +	float ymax = 1;
   1.100 +	float xmin = -1;
   1.101 +	float xmax = 1;
   1.102 +	float ticksz = 0.015;
   1.103 +
   1.104 +	glBegin(GL_LINES);
   1.105 +	glColor3f(1, 1, 1);
   1.106 +	LINE(0, -1, 0, 1);
   1.107 +	LINE(-1, 0, 1, 0);
   1.108 +
   1.109 +	for(int i=1; i<11; i++) {
   1.110 +		for(int j=0; j<2; j++) {
   1.111 +			float x = (float)i / 10.0 * (j ? -1.0 : 1.0);
   1.112 +
   1.113 +			glColor3f(0.15, 0.15, 0.15);
   1.114 +			LINE(x, ymin, x, ymax);
   1.115 +			LINE(xmin, x, xmax, x);
   1.116 +
   1.117 +			glColor3f(0.4, 0.4, 0.4);
   1.118 +			LINE(x, -ticksz, x, ticksz);
   1.119 +			LINE(-ticksz, x, ticksz, x);
   1.120 +		}
   1.121 +	}
   1.122 +	glEnd();
   1.123 +}
   1.124 +
   1.125 +void draw_label(const Vector2 &pos, const char *fmt, ...)
   1.126 +{
   1.127 +	static char buf[512];
   1.128 +	va_list ap;
   1.129 +
   1.130 +	va_start(ap, fmt);
   1.131 +	vsnprintf(buf, sizeof buf - 1, fmt, ap);
   1.132 +	va_end(ap);
   1.133 +
   1.134 +	glPushMatrix();
   1.135 +	glTranslatef(pos.x + 0.01, pos.y + 0.01, 0);
   1.136 +	float s = 2.0 / (win_ysz * zoom);
   1.137 +	glScalef(s, s, s);
   1.138 +
   1.139 +	dtx_string(buf);
   1.140 +
   1.141 +	glPopMatrix();
   1.142 +}
   1.143 +
   1.144 +void reshape(int x, int y)
   1.145 +{
   1.146 +	win_xsz = x;
   1.147 +	win_ysz = y;
   1.148 +	aspect = (float)x / (float)y;
   1.149 +
   1.150 +	glViewport(0, 0, x, y);
   1.151 +
   1.152 +	glMatrixMode(GL_PROJECTION);
   1.153 +	glLoadIdentity();
   1.154 +	glScalef(1.0 / aspect, 1.0, 1.0);
   1.155 +}
   1.156 +
   1.157 +void keyb(unsigned char key, int x, int y)
   1.158 +{
   1.159 +	keystate[key] = 1;
   1.160 +
   1.161 +	switch(key) {
   1.162 +	case 27:
   1.163 +		exit(0);
   1.164 +	}
   1.165 +}
   1.166 +
   1.167 +void keyb_up(unsigned char key, int x, int y)
   1.168 +{
   1.169 +	keystate[key] = 0;
   1.170 +}
   1.171 +
   1.172 +bool bnstate[16];
   1.173 +int prev_x, prev_y;
   1.174 +
   1.175 +void mouse(int bn, int st, int x, int y)
   1.176 +{
   1.177 +	bnstate[bn - GLUT_LEFT_BUTTON] = st == GLUT_DOWN;
   1.178 +	prev_x = x;
   1.179 +	prev_y = y;
   1.180 +
   1.181 +	if(bn == GLUT_LEFT_BUTTON && st == GLUT_DOWN) {
   1.182 +		cur_point = screen_to_world(x, y);
   1.183 +		cur_point_valid = true;
   1.184 +		glutPostRedisplay();
   1.185 +	}
   1.186 +}
   1.187 +
   1.188 +void motion(int x, int y)
   1.189 +{
   1.190 +	float dx = 2.0 * aspect * (x - prev_x) / (float)win_xsz;
   1.191 +	float dy = 2.0 * (y - prev_y) / (float)win_ysz;
   1.192 +	prev_x = x;
   1.193 +	prev_y = y;
   1.194 +
   1.195 +	if(bnstate[0]) {
   1.196 +		cur_point = screen_to_world(x, y);
   1.197 +		glutPostRedisplay();
   1.198 +	}
   1.199 +	if(bnstate[1]) {
   1.200 +		pan[0] -= dx;
   1.201 +		pan[1] += dy;
   1.202 +
   1.203 +		glutPostRedisplay();
   1.204 +	}
   1.205 +	if(bnstate[2]) {
   1.206 +		zoom += dy;
   1.207 +
   1.208 +		if(zoom < 1e-4) zoom = 1e-4;
   1.209 +		glutPostRedisplay();
   1.210 +	}
   1.211 +}
   1.212 +
   1.213 +Vector2 screen_to_world(int px, int py)
   1.214 +{
   1.215 +	float sx = 2.0 * aspect * (1.0 / zoom) / (float)win_xsz;
   1.216 +	float sy = 2.0 * (1.0 / zoom) / (float)win_ysz;
   1.217 +
   1.218 +	float x = (float)px * sx - (aspect + pan[0]) / zoom;
   1.219 +	float y = (float)(win_ysz - py) * sy - (1.0 + pan[1]) / zoom;
   1.220 +
   1.221 +	return Vector2(x, y);
   1.222 +}