以下代码显示了OpenGL C语言中的直圆柱/管道。
#include <stdio.h>
#include <stdlib.h>
#include <GL/glut.h>
#include <math.h>
#define PI 3.1415927
void draw_cylinder(GLfloat radius, GLfloat height, GLubyte R, GLubyte G, GLubyte B)
{
GLfloat x = 0.0;
GLfloat y = 0.0;
GLfloat angle = 0.0;
GLfloat angle_stepsize = 0.1;
// Draw the tube
glColor3ub(R-40,G-40,B-40);
glBegin(GL_QUAD_STRIP);
angle = 0.0;
while( angle < 2*PI ) {
x = radius * cos(angle);
y = radius * sin(angle);
glVertex3f(x, y , height);
glVertex3f(x, y , 0.0);
angle = angle + angle_stepsize;
}
glVertex3f(radius, 0.0, height);
glVertex3f(radius, 0.0, 0.0);
glEnd();
// Draw the circle on top of cylinder
glColor3ub(R,G,B);
glBegin(GL_POLYGON);
angle = 0.0;
while( angle < 2*PI ) {
x = radius * cos(angle);
y = radius * sin(angle);
glVertex3f(x, y , height);
angle = angle + angle_stepsize;
}
glVertex3f(radius, 0.0, height);
glEnd();
}
void display(void)
{
glClear(GL_COLOR_BUFFER_BIT);
glLoadIdentity();
glTranslatef(-0.5,0.0,-2.5);
glRotatef(100.0, 0.725, 1.0, 1.0);
draw_cylinder(0.15, 1.0, 255, 160, 100);
glFlush();
}
void reshape(int width, int height)
{
if (width == 0 || height == 0) return;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(35.0, (GLdouble)width/(GLdouble)height,0.5, 20.0);
glMatrixMode(GL_MODELVIEW);
glViewport(0, 0, width, height);
}
int main(int argc, char **argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize(640,580);
glutCreateWindow("Create Cylinder");
glClearColor(0.0,0.0,0.0,0.0);
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutMainLoop();
return 0;
}
此刻,它绘制了笔直的圆柱体/管道。我想将其弯曲成this。
答案 0 :(得分:2)
首先,我建议将圆柱体切成薄片。下一个圆锥体将绘制完全相同的圆柱体,但会拆分圆柱体int切片。切片具有不同的颜色以显现效果。
GLfloat h0, h1, angle, x, y;
int i, j;
int slices = 8;
for ( i = 0; i < slices; i++ )
{
h0 = (float)i / (float)slices;
h1 = (float)(i+1) / (float)slices;
glColor3f( 1.0f-h0, 0.0, h1 );
glBegin(GL_QUAD_STRIP);
for ( j = 0; j <= 360; ++ j )
{
angle = PI * (float)j * PI / 180.0f;
x = radius * cos(angle);
y = radius * sin(angle);
glVertex3f( x, y, h0 );
glVertex3f( x, y, h1 );
}
glEnd();
}
然后,您必须定义弯曲半径以及弯曲开始和结束角度。以下代码绘制了半径为bend_ang0
的弯曲bend_ang1
至bend_radius
的弯管形状。可以根据弯曲半径和管道长度来计算弯曲角度:
GLfloat w0, w1, ang0, ang1, angle, x, y, xb, yb, zb;
int i, j;
int slices = 8;
GLfloat bend_radius = 1.0f;
GLfloat bend_angle, bend_ang0, bend_ang1;
bend_angle = bend_radius * height;
bend_ang0 = -bend_angle/2.0f;
bend_ang1 = bend_angle/2.0f;
for ( i = 0; i < slices; i++ )
{
w0 = (float)i / (float)slices;
w1 = (float)(i+1) / (float)slices;
ang0 = bend_ang0 + (bend_ang1-bend_ang0) * w0;
ang1 = bend_ang0 + (bend_ang1-bend_ang0) * w1;
glColor3f( 1.0f-w0, 0.0, w1 );
glBegin(GL_QUAD_STRIP);
for ( j = 0; j <= 360; ++ j )
{
angle = PI * (float)j * PI / 180.0f;
x = radius * cos(angle) + bend_radius;
y = radius * sin(angle);
xb = sin( ang0 ) * x;
yb = y;
zb = cos( ang0 ) * x;
glVertex3f( xb, yb, zb );
xb = sin( ang1 ) * x;
yb = y;
zb = cos( ang1 ) * x;
glVertex3f( xb, yb, zb );
}
glEnd();
}
对于以下图像,我激活了深度测试并更改了模型视图矩阵:
void display(void)
{
glEnable( GL_DEPTH_TEST );
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
glTranslatef(0.0f, -0.5f, -4.0f);
glRotatef(-90.0f, 1.0f, 0.0, 0.0f);
draw_cylinder(0.15, 2.0, 255, 160, 100);
glFlush();
}
答案 1 :(得分:1)
当前,您要一次性绘制圆柱的整个高度...要创建曲面,您必须改用现有代码,并创建一系列连续的微小圆柱,每个圆柱的高度都很小,然后将它们堆叠到消耗原始高度。
一种方法是引入一个新功能,使其成为您的
的父级void draw_cylinder(GLfloat radius, GLfloat height, GLubyte R, GLubyte G, GLubyte B)
也许叫它
draw_curved_cylinder
在这个新函数中,您有一个循环,您可以在其中调用draw_cylinder
并为其指定每个小圆柱的参数...当前,您的draw函数将高度从0盲目拉伸到给定的{{1 }} ...将其替换为给定的小圆柱体的设置...还要使最终的圆柱体弯曲,每个小圆柱体的X和Y坐标必须遵循弯曲的轨迹,以便在新功能height
中增加因此随着您合成每个新的小圆柱体而有所不同
PS-请注意您没有在使用现代OpenGL-glBegin已过时,应避免使用