Situatie
In this, a ball is moving starting from middle and goes to up-left in starting. But, then it collides with wall and changes direction but speed remain same. Consequently, it comes to downward direction where it should be catched on a rectangle (which is capable of moving in horizontal direction) in order to continue.
Solutie
Pasi de urmat
// C program to illustrate OpenGL game #include<stdio.h> #include<GL/glut.h> #include<math.h> #define pi 3.142857 // Global Declaration // c and d tracks the number of time 'b' and 'n' pressed respectively // left and right indicates leftmost and rightmost index of movable rectangle int c = 0, d = 0, left = 0, right = 0; int m = 0, j = 1, flag1 = 0, l = 1, flag2 = 0, n = 0, score = 0, count = 1; // Initialization function void myInit (void) { // Reset background color with white (since all three argument is 1.0) glClearColor(1.0, 1.0, 1.0, 0.0); // Set picture color to red (in RGB model) // as only argument corresponding to R (Red) is 1.0 and rest are 0.0 glColor3f(1.0f, 0.0f, 0.0f); // Set width of point to one unit glPointSize(1.0); glMatrixMode(GL_PROJECTION); glLoadIdentity(); // Set window size in X- and Y- direction gluOrtho2D(-620.0, 620.0, -340.0, 340.0); } // keyboard function : it gets active when button pressed void keyboard(unsigned char key, int x, int y) { left = -200 + 200 * (d - c); right = 200 + 200 * (d - c); // if leftmost index of window is hit // then rectangle will not move to left on furthure pressing of b // only it will move to right on pressing n if (left == -600) { // '110' -> Ascii value of 'n' // so d is incremented when n is pressed if (key == 110) d++; } // if rightmost index of window is hit // then rectangle will not move to right on furthure pressing of n // only it will move to left on pressing b else if (right == 600) { // '98' -> Ascii value of 'b' // so c is incremented when b is pressed if (key == 98) c++; } // when rectangle is in middle, then it will move into both // direction depending upon pressed key else { if (key == 98) c++; if (key == 110) d++; } glutPostRedisplay(); } void myDisplay(void) { // x and y keeps point on circumference of circle int x, y, k; // outer 'for loop' is to for making motion in ball for (k = 0; k <= 400; k += 5) { glClear(GL_COLOR_BUFFER_BIT); glBegin(GL_LINE_STRIP); // i keeps track of angle float i = 0; // change in m denotes motion in vertical direction and // change in n denotes motion in horizontal direction m = m + 6; n = n + 4; // drawing of circle centre at (0, 12) iterated up to 2*pi, i.e., 360 degree while (i <= 2 * pi) { y = 12 + 20 * cos(i); x = 20 * sin(i); i = i + 0.1; // flag1 is 0 to show motion in upward direction and is 1 for downward direction if (m == 288 && flag1 == 0) { j = -1; m = -288; flag1 = 1; score++; } if (m == 288 && flag1 == 1) { j = 1; m = -288; flag1 = 0; } // flag2 is 0 to show motion in rightward direction and is 1 for leftward direction if (n == 580 && flag2 == 0) { l = -1; n = -580; flag2 = 1; } if (n == 580 && flag2 == 1) { l = 1; n = -580; flag2 = 0; } // equation for desired motion of ball glVertex2i((x - l * n), (y - j * m)); } glEnd(); // these four points draws outer rectangle which determines window glBegin(GL_LINE_LOOP); glVertex2i(-600, -320); glVertex2i(-600, 320); glVertex2i(600, 320); glVertex2i(600, -320); glEnd(); // these four points draws smaller rectangle which is for catching ball glBegin(GL_LINE_LOOP); left = -200 + 200 * (d - c); right = 200 + 200 * (d - c); glVertex2i(left, -315); glVertex2i(left, -295); glVertex2i(right, -295); glVertex2i(right, -315); glEnd(); // following condition checks if falling ball is catched on rectangle or not if ((j * m) == 276) { if ((left > ((-1 * l * n) + 20)) || (right < (-1 * l * n) - 20)) { printf("Game Over !!!\nYour Score is :\t%d\n", score); exit(0); } } glutSwapBuffers(); } } // Driver Program int main (int argc, char** argv) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA); // Declares window size glutInitWindowSize(1100, 600); // Declares window position which is (0, 0) // means lower left corner will indicate position (0, 0) glutInitWindowPosition(0, 0); // Name to window glutCreateWindow("Game"); // keyboard function glutKeyboardFunc(keyboard); // Call to myInit() myInit(); glutDisplayFunc(myDisplay); glutMainLoop(); } Below is the screenshot of the animation. This screenshot is of one instance. In actual, ball will move in different direction which should be catched on the smaller rectangle. Rectangle can be moved to left by pressing lowercase b and towards right by lowercase n. However, this can be changed by changing the code in keyboard function where ASCII value of key can be changed.
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