Я сравниваю предыдущие вопросы, у вас отключен тест глубины.Я рекомендую снова включить тест dept и нарисовать объект с различной глубиной (координаты z).
Если вы не хотите включать тест глубины, сначала вы должны нарисовать фон, а затем всплывающую подсказку.и наконец дождь:
void display() {
glClear(GL_COLOR_BUFFER_BIT);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
// draw background
drawBackground();
// draw hot air balloon
glPushMatrix();
drawAirBalloon();
glPopMatrix();
// draw rain
drawRain();
calcFPS();
counter++;
glFlush();
glutSwapBuffers();
glutPostRedisplay();
}
Далее вы должны удалить glClear из drawAirBalloon:
void drawAirBalloon(void) {
// .....
// glClear(GL_COLOR_BUFFER_BIT); <---- delete this
И glFlush from фон рисования
void drawBackground() {
// .....
// glFlush(); <---- delete this, too
}
Обратите внимание, что произвольные glClear и glFlush в середине рендеринга вызовут частичный рендеринг и мерцание (особенно при использовании одиночной буферизации).
Финальный код:
#include <stdio.h> // this library is for standard input and output
#include <stdlib.h>
#include <time.h>
#include <math.h>
#include "glut.h"// this library is for glut the OpenGL Utility Toolkit
float squareX = 0.0f;
float squareY = -0.3f;
float squareZ = 0.0f;
static int flag = 1;
#define RAINSIZE 200
int winWidth = 800, winHeight = 600;
int counter = 0;
time_t t;
float rotationAngle = 0;
struct drop {
float x = 400;
float y = 400;
float inc = 0.01;
float radius = 5;
float scale = 1.0;
float rotationAngle = 0;
float rotationInc = 1;
};
drop rain[RAINSIZE];
void initRain() {
srand((unsigned)time(&t));
for (int i = 0; i < RAINSIZE; i++) {
rain[i].x = rand() % winWidth;
rain[i].y = rand() % winHeight;
rain[i].inc = 1.5 + (float)(rand() % 100) / 1000.0;
rain[i].radius = (float)(rand() % 8);
rain[i].scale = (float)(rand() % 20000) / 1000.0;
rain[i].rotationAngle = (float)(rand() % 3000) / 1000.0;
rain[i].rotationInc = (float)(rand() % 100) / 1000.0;
if ((rand() % 100) > 50) {
rain[i].rotationInc = -rain[i].rotationInc;
}
}
}
void drawParticleShape(int i) {
glBegin(GL_POINTS);
glVertex2d(rain[i].x, rain[i].y);
glEnd();
glBegin(GL_LINES);
glVertex2d(rain[i].x, rain[i].y);
glVertex2d(rain[i].x, rain[i].y + rain[i].radius * 2);
glEnd();
}
void drawDrop(int i) {
// color of the rain
glColor3f(0.1, 0.6, 0.8);
glLineWidth(2);
drawParticleShape(i);
rain[i].y -= rain[i].inc;
if (rain[i].y < 0) {
rain[i].y = winHeight;
}
}
void drawRain() {
for (int i = 0; i < RAINSIZE; i++) {
drawDrop(i);
}
}
// this is the initialisation function, called once only
void init() {
glClearColor(0.0, 0.0, 0.0, 0.0); // set what colour you want the background to be
glMatrixMode(GL_PROJECTION); // set the matrix mode, we will look at this later
// set the projection window size in x an y.
gluOrtho2D(0.0, winWidth, 0.0, winHeight);
}
float elapsedTime = 0, base_time = 0, fps = 0, frames;
void calcFPS() {
elapsedTime = glutGet(GLUT_ELAPSED_TIME);
if ((elapsedTime - base_time) > 1000.0) {
fps = frames * 1000.0 / (elapsedTime - base_time);
base_time = elapsedTime;
frames = 0;
}
frames++;
}
// the background
void drawBackground() {
// draw the green ground
glBegin(GL_POLYGON);
glColor3f(0.3, 0.7, 0.0);
glVertex2f(800, 100);
glVertex2f(800, 0);
glVertex2f(0, 0);
glVertex2f(0, 100);
glVertex2f(800, 100);
glEnd();
// draw the blue sky
glBegin(GL_POLYGON);
glColor3f(0.7, 0.7, 0.9);
glVertex2f(800, 100);
glVertex2f(800, 800);
glVertex2f(0, 800);
glVertex2f(0, 100);
glVertex2f(800, 100);
glEnd();
//glFlush();
}
// the hot air balloon
void drawAirBalloon(void) {
glTranslatef(squareX, squareY, squareZ);
// draw the balloon
float theta;
int cutsegment = 45;
int start = -90 + cutsegment / 2;
int end = 270 - cutsegment / 2;
//glClear(GL_COLOR_BUFFER_BIT);
glBegin(GL_POLYGON);
glColor3f(1.0, 0.0, 0.0);
for (int i = -45; i <= 225; i++) {
theta = i * 3.142 / 180;
glVertex2f(355 + 70 * cos(theta), 225 + 90 * sin(theta));
}
glEnd();
// draw first rope on the left
glBegin(GL_LINES);
glColor3f(0.0, 0.0, 0.0);
glVertex2f(320, 95);
glVertex2f(295, 177);
glEnd();
// draw first rope on the right
glBegin(GL_LINES);
glColor3f(0.0, 0.0, 0.0);
glVertex2f(415, 180);
glVertex2f(390, 95);
glEnd();
// draw propane burner
glBegin(GL_POLYGON);
glColor3f(0.1, 0.1, 0.1);
glVertex2f(335, 140);
glVertex2f(335, 120);
glVertex2f(375, 120);
glVertex2f(375, 140);
glVertex2f(335, 140);
glEnd();
// first vertical line on basket
glBegin(GL_LINES);
glColor3f(0.6, 0.25, 0.1);
glVertex2f(330, 95);
glVertex2f(330, 40);
glEnd();
// second vertical line on basket
glBegin(GL_LINES);
glColor3f(0.6, 0.25, 0.1);
glVertex2f(340, 95);
glVertex2f(340, 40);
glEnd();
// third vertical line on basket
glBegin(GL_LINES);
glColor3f(0.6, 0.25, 0.1);
glVertex2f(350, 95);
glVertex2f(350, 40);
glEnd();
// fourth vertical line on basket
glBegin(GL_LINES);
glColor3f(0.6, 0.25, 0.1);
glVertex2f(360, 95);
glVertex2f(360, 40);
glEnd();
// fifth vertical line on basket
glBegin(GL_LINES);
glColor3f(0.6, 0.25, 0.1);
glVertex2f(370, 95);
glVertex2f(370, 40);
glEnd();
// sixth vertical line on basket
glBegin(GL_LINES);
glColor3f(0.6, 0.25, 0.1);
glVertex2f(380, 95);
glVertex2f(380, 40);
glEnd();
// first horizontal line on basket
glBegin(GL_LINES);
glColor3f(0.6, 0.25, 0.1);
glVertex2f(390, 80);
glVertex2f(320, 80);
glEnd();
// second horizontal line on basket
glBegin(GL_LINES);
glColor3f(0.6, 0.25, 0.1);
glVertex2f(390, 55);
glVertex2f(320, 55);
glEnd();
// draw basket
glBegin(GL_POLYGON);
glColor3f(0.6, 0.45, 0.1);
glVertex2f(320, 95);
glVertex2f(320, 40);
glVertex2f(390, 40);
glVertex2f(390, 95);
glVertex2f(320, 95);
glEnd();
}
// move the hot air balloon up
void update(int value) {
if (flag) {
squareY += 1.0f;
if (squareY > 350.0) {
flag = 0;
}
}
glutPostRedisplay();
glutTimerFunc(25, update, 0);
}
// This is the display function it is called when ever you want to draw something
// all drawing should be called form here
void display() {
glClear(GL_COLOR_BUFFER_BIT);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
// draw background
drawBackground();
// draw hot air balloon
glPushMatrix();
drawAirBalloon();
glPopMatrix();
// draw rain
drawRain();
calcFPS();
counter++;
glFlush();
glutSwapBuffers();
glutPostRedisplay();
}
// This is the idle function it is called whenever the program is idle
// This has the effect of repeatedly calling the display function
void idle() {
display();
}
// As with many programming languages the main() function
// is the entry point for execution of the program
int main(int argc, char** argv) {
srand(1);
initRain();
glutInit(&argc, argv); //perform the GLUT initialization
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGBA); // more initialisation
glutInitWindowSize(winWidth, winHeight); // set window position
glutInitWindowPosition(0, 0); // set window size
glutCreateWindow("Hot Air Balloon"); // create a display with a given caption for the title bar
glEnable(GL_BLEND); //Enable blending.
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); //Set blending function.
init(); // call init function defined above
glutIdleFunc(idle); // define what function to call when the program is idle
glutDisplayFunc(display); // define what function to call to draw
glutTimerFunc(25, update, 0);
// the last function in the program puts the program into infinite loop
glutMainLoop();
// this line exits the program
return 0;
}