Help end child hunger

The Code So Far V

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This code is similar to the one presented for bitmap fonts. The differences are that it uses stroke fonts to display the numbers on top of each snowman, and it displays, using orthographic projection, a text using bitmap fonts. This latter text, which includes the number of frames per second, is not affected by the camera motion, it stays always in the same position on the screen.

The font menu has also been altered to use stroke fonts instead of bitmap fonts.

As usual, copy and paste this code into your project, or go to the download section, if you want to try it.

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#ifdef __APPLE__
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif

// angle of rotation for the camera direction
float angle = 0.0f;

// actual vector representing the camera's direction
float lx=0.0f,lz=-1.0f;

// XZ position of the camera
float x=0.0f, z=5.0f;

// the key states. These variables will be zero
//when no key is being presses
float deltaAngle = 0.0f;
float deltaMove = 0;
int xOrigin = -1;

// Constant definitions for Menus
#define RED 1
#define GREEN 2
#define BLUE 3
#define ORANGE 4

#define FILL 1
#define LINE 2

// Pop up menu identifiers
int fillMenu, fontMenu, mainMenu, colorMenu;

// color for the nose
float red = 1.0f, blue=0.5f, green=0.5f;

// scale of snowman
float scale = 1.0f;

// menu status
int menuFlag = 0;

// default font
void *font = GLUT_STROKE_ROMAN;

// width and height of the window
int h,w;

// variables to compute frames per second
int frame;
long time, timebase;
char s[50];

void changeSize(int ww, int hh) {

	h = hh;
	w = ww;
	// Prevent a divide by zero, when window is too short
	// (you cant make a window of zero width).
	if (h == 0)
		h = 1;

	float ratio =  w * 1.0 / h;

	// Use the Projection Matrix
	glMatrixMode(GL_PROJECTION);

	// Reset Matrix
	glLoadIdentity();

	// Set the viewport to be the entire window
	glViewport(0, 0, w, h);

	// Set the correct perspective.
	gluPerspective(45.0f, ratio, 0.1f, 100.0f);

	// Get Back to the Modelview
	glMatrixMode(GL_MODELVIEW);
}

void drawSnowMan() {

	glScalef(scale, scale, scale);
	glColor3f(1.0f, 1.0f, 1.0f);

// Draw Body
	glTranslatef(0.0f ,0.75f, 0.0f);
	glutSolidSphere(0.75f,20,20);

// Draw Head
	glTranslatef(0.0f, 1.0f, 0.0f);
	glutSolidSphere(0.25f,20,20);

// Draw Eyes
	glPushMatrix();
	glColor3f(0.0f,0.0f,0.0f);
	glTranslatef(0.05f, 0.10f, 0.18f);
	glutSolidSphere(0.05f,10,10);
	glTranslatef(-0.1f, 0.0f, 0.0f);
	glutSolidSphere(0.05f,10,10);
	glPopMatrix();

// Draw Nose
	glColor3f(red, green, blue);
	glRotatef(0.0f,1.0f, 0.0f, 0.0f);
	glutSolidCone(0.08f,0.5f,10,2);

	glColor3f(1.0f, 1.0f, 1.0f);

}

void renderBitmapString(
		float x,
		float y,
		float z,
		void *font,
		char *string) {

	char *c;
	glRasterPos3f(x, y,z);
	for (c=string; *c != '\0'; c++) {
		glutBitmapCharacter(font, *c);
	}
}

void renderStrokeFontString(
		float x,
		float y,
		float z,
		void *font,
		char *string) {  

	char *c;
	glPushMatrix();
	glTranslatef(x, y,z);
	glScalef(0.002f, 0.002f, 0.002f);
	for (c=string; *c != '\0'; c++) {
		glutStrokeCharacter(font, *c);
	}
	glPopMatrix();
}

void restorePerspectiveProjection() {

	glMatrixMode(GL_PROJECTION);
	// restore previous projection matrix
	glPopMatrix();

	// get back to modelview mode
	glMatrixMode(GL_MODELVIEW);
}

void setOrthographicProjection() {

	// switch to projection mode
	glMatrixMode(GL_PROJECTION);

	// save previous matrix which contains the
	//settings for the perspective projection
	glPushMatrix();

	// reset matrix
	glLoadIdentity();

	// set a 2D orthographic projection
	gluOrtho2D(0, w, h, 0);

	// switch back to modelview mode
	glMatrixMode(GL_MODELVIEW);
}

void computePos(float deltaMove) {

	x += deltaMove * lx * 0.1f;
	z += deltaMove * lz * 0.1f;
}

void renderScene(void) {

	if (deltaMove)
		computePos(deltaMove);

	// Clear Color and Depth Buffers
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

	// Reset transformations
	glLoadIdentity();
	// Set the camera
	gluLookAt(	x, 1.0f, z,
			x+lx, 1.0f,  z+lz,
			0.0f, 1.0f,  0.0f);

// Draw ground

	glColor3f(0.9f, 0.9f, 0.9f);
	glBegin(GL_QUADS);
		glVertex3f(-100.0f, 0.0f, -100.0f);
		glVertex3f(-100.0f, 0.0f,  100.0f);
		glVertex3f( 100.0f, 0.0f,  100.0f);
		glVertex3f( 100.0f, 0.0f, -100.0f);
	glEnd();

// Draw 36 SnowMen
	char number[3];
	for(int i = -3; i < 3; i++)
		for(int j=-3; j < 3; j++) {
			glPushMatrix();
			glTranslatef(i*10.0f, 0.0f, j * 10.0f);
			drawSnowMan();
			sprintf(number,"%d",(i+3)*6+(j+3));
			renderStrokeFontString(0.0f, 0.5f, 0.0f, (void *)font ,number);
			glPopMatrix();
		}

	// Code to compute frames per second
	frame++;

	time=glutGet(GLUT_ELAPSED_TIME);
	if (time - timebase > 1000) {
		sprintf(s,"Lighthouse3D - FPS:%4.2f",
			frame*1000.0/(time-timebase));
		timebase = time;
		frame = 0;
	}

        // Code to display a string (fps) with bitmap fonts
	setOrthographicProjection();

	glPushMatrix();
	glLoadIdentity();
	renderBitmapString(5,30,0,GLUT_BITMAP_HELVETICA_18,s);
	glPopMatrix();

	restorePerspectiveProjection();

	glutSwapBuffers();
}

// -----------------------------------
//             KEYBOARD
// -----------------------------------

void processNormalKeys(unsigned char key, int xx, int yy) {

	switch (key) {
		case 27:
			glutDestroyMenu(mainMenu);
			glutDestroyMenu(fillMenu);
			glutDestroyMenu(colorMenu);
			glutDestroyMenu(fontMenu);
			exit(0);
			break;
	}
}

void pressKey(int key, int xx, int yy) {

	switch (key) {
		case GLUT_KEY_UP : deltaMove = 0.5f; break;
		case GLUT_KEY_DOWN : deltaMove = -0.5f; break;
	}
}

void releaseKey(int key, int x, int y) {

	switch (key) {
		case GLUT_KEY_UP :
		case GLUT_KEY_DOWN : deltaMove = 0;break;
	}
}

// -----------------------------------
//             MOUSE
// -----------------------------------

void mouseMove(int x, int y) {

	// this will only be true when the left button is down
	if (xOrigin >= 0) {

		// update deltaAngle
		deltaAngle = (x - xOrigin) * 0.001f;

		// update camera's direction
		lx = sin(angle + deltaAngle);
		lz = -cos(angle + deltaAngle);
	}
}

void mouseButton(int button, int state, int x, int y) {

	// only start motion if the left button is pressed
	if (button == GLUT_LEFT_BUTTON) {

		// when the button is released
		if (state == GLUT_UP) {
			angle += deltaAngle;
			xOrigin = -1;
		}
		else  {// state = GLUT_DOWN
			xOrigin = x;
		}
	}
}

// -----------------------------------
//             MENUS
// -----------------------------------

void processMenuStatus(int status, int x, int y) {

	if (status == GLUT_MENU_IN_USE)
		menuFlag = 1;
	else
		menuFlag = 0;
}

void processMainMenu(int option) {

	// nothing to do in here
	// all actions are for submenus
}

void processFillMenu(int option) {

	switch (option) {

		case FILL: glPolygonMode(GL_FRONT, GL_FILL); break;
		case LINE: glPolygonMode(GL_FRONT, GL_LINE); break;
	}
}

void processFontMenu(int option) {

	switch (option) {
		case 1: font = GLUT_STROKE_ROMAN;
			break;
		case 2: font = GLUT_STROKE_MONO_ROMAN;
			break;
	}
}

void processColorMenu(int option) {

	switch (option) {
		case RED :
			red = 1.0f;
			green = 0.0f;
			blue = 0.0f; break;
		case GREEN :
			red = 0.0f;
			green = 1.0f;
			blue = 0.0f; break;
		case BLUE :
			red = 0.0f;
			green = 0.0f;
			blue = 1.0f; break;
		case ORANGE :
			red = 1.0f;
			green = 0.5f;
			blue = 0.5f; break;
	}
}

void createPopupMenus() {

	fontMenu = glutCreateMenu(processFontMenu);

        glutAddMenuEntry("STROKE_ROMAN",1 );
        glutAddMenuEntry("STROKE_MONO_ROMAN",2 );
	fillMenu = glutCreateMenu(processFillMenu);

	glutAddMenuEntry("Fill",FILL);
	glutAddMenuEntry("Line",LINE);

	colorMenu = glutCreateMenu(processColorMenu);
	glutAddMenuEntry("Red",RED);
	glutAddMenuEntry("Blue",BLUE);
	glutAddMenuEntry("Green",GREEN);
	glutAddMenuEntry("Orange",ORANGE);

	mainMenu = glutCreateMenu(processMainMenu);

	glutAddSubMenu("Polygon Mode", fillMenu);
	glutAddSubMenu("Color", colorMenu);
	glutAddSubMenu("Font",fontMenu);
	// attach the menu to the right button
	glutAttachMenu(GLUT_RIGHT_BUTTON);

	// this will allow us to know if the menu is active
	glutMenuStatusFunc(processMenuStatus);
}

// -----------------------------------
//             MAIN
// -----------------------------------

int main(int argc, char **argv) {

	// init GLUT and create window
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
	glutInitWindowPosition(100,100);
	glutInitWindowSize(320,320);
	glutCreateWindow("Lighthouse3D - GLUT Tutorial");

	// register callbacks
	glutDisplayFunc(renderScene);
	glutReshapeFunc(changeSize);
	glutIdleFunc(renderScene);

	glutIgnoreKeyRepeat(1);
	glutKeyboardFunc(processNormalKeys);
	glutSpecialFunc(pressKey);
	glutSpecialUpFunc(releaseKey);

	// here are the two new functions
	glutMouseFunc(mouseButton);
	glutMotionFunc(mouseMove);

	// OpenGL init
	glEnable(GL_DEPTH_TEST);
	glEnable(GL_CULL_FACE);

	// init Menus
	createPopupMenus();

	// enter GLUT event processing cycle
	glutMainLoop();
	
	return 1;
}

 

Prev: Frames Per Second Next: Game Mode
 

5 Responses to “The Code So Far V”

  1. I’ve figured it out. You’ve also now set “h” & “w” as global variables instead of local to “changeSize”, and these global variables are used in “setOrthographicProjection”.
    It would be easier to understand if you introduced “ww” & “hh” as the new global variables,and used them in “setOrthographicProjection”. The “changeSize” function would then continue to use “h” & “w” as its arguments, but would just need 2 code lines to set the globals as follows:-
    ww = w;
    hh = h;

  2. In this code you have altered the “changeSize” function by introducing “hh” & “ww”.
    Without this change the Frames per Second text does not appear in the window.
    Please can you explain why.

  3. I really dont know why, but it`s give me segmentation fault

  4. You’re using a non standard way if converting pointers to integers. I’m on linux and the compiler gives me an error:
    error: cast from ‘void*’ to ‘int’ loses precision
    I’ve played around with it a little but couldnt get it to work correctly.
    Here are some possible answers:
    http://stackoverflow.com/questions/1640423/error-cast-from-void-to-int-loses-precision
    Compiling does work for me now but the integers only contain zeros, not a valid font.

    • Yes, you’re right. Thanks for pointing it out. Windows lets you do that …

      The code has been updated to address this issue.

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