我在OpenGL的制作程序在曲线动画固球
它是这样
//显示功能
void display()
{
glClear(GL_DEPTH_BUFFER_BIT|GL_COLOR_BUFFER_BIT);
glLoadIdentity();
//set of condition
loop:j=1 to 5
loop:i=1 to 3
if(j==1)
{
animate(x,y,z)
glutSwapBuffers();
}
elseif(j==5)
{
animate(x,y,z)
glutSwapBuffers();
}
else //for all value j between 1 and 5
{
animate(x,y,z);
glutSwapBuffers();
}
}
//animate function
void animate(float x, float y, float z)
{
glLoadIdentity();
glTranslatef(0,0,-20);
glPushMatrix();
glTranslatef (x, y, z);
glutSolidSphere (0.3, 10, 10);
int i, j;
for(i = 0; i < 10000; i++) //for introducing delay
for(j = 0; j < 5000; j++);
glPopMatrix();
glutSwapBuffers();
}
问题：实心球被翻译曲线上，但其每一个位置，如果球从像P1，P2，P3，P4和P5 THEN位置顺序去我不能够删除其先前的位置......例如。 。之后来到位置P5其在其他所有以前的位置（P1，P2，P3，P4），但我希望它只是在当前位置显示领域，而翻译我怎样才能做到这一点仍清晰可见？
你是不是清除帧缓冲，这意味着你吸取了前一帧的顶部每一帧。 尝试使用glClearColor(0.0f, 0.0f, 0.0f, 1.0f ); 用颜色你的愿望。
OpenGL是不是一个场景图。 它所做的就是着色像素。 当你发送一些几何图形，以OpenGL和它处理它，它走了，忘了，所有剩下什么是它在帧缓存的痕迹。 需要注意的是一个顶点缓冲对象的内容不被几何本身。 只有图纸电话（glDrawElements， 调用glDrawArrays）依次顶点缓冲区进入几何值。
另外你的程序不遵循典型的动画循环。 你这样做是正确的，现在不允许用户交互的方式，或在动画过程中的任何其他类型的事件处理。 你应该改变你的代码如下：
static timeval delta_T = {0., 0.};
struct AnimationState {
// ...
float sphere_position[3];
};
AnimationState animation;
void display()
{
// Start time, frame rendering begins:
timeval time_begin_frame;
gettimeofday(&time_begin_frame, 0);
animate(delta_T.tv_sec + delta_T.tv_usec * 1.e6);
glClear(GL_DEPTH_BUFFER_BIT|GL_COLOR_BUFFER_BIT);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
set_projection();
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
apply_camera_transform();
draw_sphere(animation.sphere_position[0],
animation.sphere_position[1],
animation.sphere_position[2])
glutSwapBuffers();
// frame render end time
timeval time_end_frame;
gettimeofday(&time_end_frame, 0);
timersub(&time_end_frame, &time_begin_frame, &delta_time);
}
void draw_sphere(float x, float y, float z)
{
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glTranslatef (x, y, z);
glutSolidSphere (0.3, 10, 10);
glPopMatrix();
}
void animate(float dT)
{
// advance animation by timestep dT
}
void idle()
{
glutPostRedisplay();
}
编辑完整的工作代码示例
/* sinsphere.c */
#include <GL/glut.h>
#include <stdlib.h>
#include <sys/time.h>
#include <math.h>
#define M_PI 3.1415926535897932384626433832795029L
#define M_PI_2 1.5707963267948966192313216916397514L
# define timersub(a, b, result) \
do { \
(result)->tv_sec = (a)->tv_sec - (b)->tv_sec; \
(result)->tv_usec = (a)->tv_usec - (b)->tv_usec; \
if ((result)->tv_usec < 0) { \
--(result)->tv_sec; \
(result)->tv_usec += 1000000; \
} \
} while (0)
void idle(void);
void animate(float dT);
void display(void);
void init_sphere(unsigned int rings, unsigned int sectors);
void draw_sphere(void);
int main(int argc, char *argv[])
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE);
glutCreateWindow("SinSphere");
glutIdleFunc(idle);
glutDisplayFunc(display);
init_sphere(10, 30);
glutMainLoop();
return 0;
}
struct AnimationState
{
float time;
float sphere_speed;
float sphere_path_radius;
float sphere_path_bobbing;
float sphere_position[3];
};
static struct AnimationState animation = {
0.,
0.1, 3., 1.,
{1., 0., 0.}
};
void animate(float dT)
{
animation.time += dT;
animation.sphere_position[0] = animation.sphere_path_radius * cos(2*M_PI * animation.time * animation.sphere_speed);
animation.sphere_position[1] = animation.sphere_path_bobbing * sin(2*M_PI * animation.time * 5 * animation.sphere_speed);
animation.sphere_position[2] = animation.sphere_path_radius * sin(2*M_PI * animation.time * animation.sphere_speed);
}
GLfloat *sphere_vertices_normals;
unsigned int sphere_quads = 0;
GLushort *sphere_indices;
void init_sphere(unsigned int rings, unsigned int sectors)
{
float const R = 1./(float)(rings-1);
float const S = 1./(float)(sectors-1);
int r, s;
sphere_vertices_normals = malloc(sizeof(GLfloat)*3 * rings*sectors);
GLfloat *v = sphere_vertices_normals;
for(r = 0; r < rings; r++) for(s = 0; s < sectors; s++) {
float const y = sin( -M_PI_2 + M_PI * r * R );
float const x = cos(2*M_PI * s * S) * sin( M_PI * r * R );
float const z = sin(2*M_PI * s * S) * sin( M_PI * r * R );
v[0] = x;
v[1] = y;
v[2] = z;
v+=3;
}
sphere_indices = malloc(sizeof(GLushort) * rings * sectors * 4);
GLushort *i = sphere_indices;
for(r = 0; r < rings; r++) for(s = 0; s < sectors; s++) {
*i++ = r * sectors + s;
*i++ = r * sectors + (s+1);
*i++ = (r+1) * sectors + (s+1);
*i++ = (r+1) * sectors + s;
sphere_quads++;
}
}
void draw_sphere()
{
glTranslatef(animation.sphere_position[0], animation.sphere_position[1], animation.sphere_position[2]);
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_NORMAL_ARRAY);
glVertexPointer(3, GL_FLOAT, 0, sphere_vertices_normals);
glNormalPointer(GL_FLOAT, 0, sphere_vertices_normals);
glDrawElements(GL_QUADS, sphere_quads*4, GL_UNSIGNED_SHORT, sphere_indices);
}
void idle()
{
glutPostRedisplay();
}
static GLfloat const light_pos[4] = {-1., 1., 1., 0.};
static GLfloat const light_color[4] = {1., 1., 1., 1.};
void display()
{
static struct timeval delta_T = {0., 0.};
struct timeval time_frame_begin, time_frame_end;
int win_width, win_height;
float win_aspect;
gettimeofday(&time_frame_begin, 0);
animate(delta_T.tv_sec + delta_T.tv_usec * 1.e-6);
win_width = glutGet(GLUT_WINDOW_WIDTH);
win_height = glutGet(GLUT_WINDOW_HEIGHT);
win_aspect = (float)win_width/(float)win_height;
glViewport(0, 0, win_width, win_height);
glClearColor(0.6, 0.6, 1.0, 1.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glFrustum(-win_aspect, win_aspect, -1., 1., 1., 10.);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glTranslatef(0,0,-5.5);
glLightfv(GL_LIGHT0, GL_POSITION, light_pos);
glLightfv(GL_LIGHT0, GL_DIFFUSE, light_color);
glPushMatrix();
glEnable(GL_DEPTH_TEST);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
draw_sphere();
glPopMatrix();
glutSwapBuffers();
gettimeofday(&time_frame_end, 0);
timersub(&time_frame_end, &time_frame_begin, &delta_T);
}
