| 发表于：2007-12-30 21:04:32 楼主 |
我最近刚刚开始看opengl，以下的程序是《opengl超级宝典》上第3章的一个例子，输出的结果应该是一个螺旋曲线。但是在我的电脑上输出的结果却只是一个大的、中间为空心的的圆饼。我想请问一下各位是什么原因（是不是硬件原因）？
我的电脑主板名称 asus p5pe-vm
显示卡（主板集成) intel 82865g graphics controller [a-2]
程序如下：
// pointsz.c
// opengl superbible, chapter 4
// demonstrates opengl primative gl_points with point size
// program by richard s. wright jr.
#include <windows.h>
#include <gl/gl.h>
#include <gl/glu.h>
#include <gl/glut.h>
#include <math.h>
// define a constant for the value of pi
#define gl_pi 3.1415f
// rotation amounts
static glfloat xrot = 0.0f;
static glfloat yrot = 0.0f;
// called to draw scene
void renderscene（void)
{
glfloat x,y,z,angle; // storeage for coordinates and angles
glfloat sizes[2]; // store supported point size range
glfloat step; // store supported point size increments
glfloat cursize; // store current size
// clear the window with current clearing color
glclear（gl_color_buffer_bit);
// save matrix state and do the rotation
glpushmatrix（);
glrotatef（xrot, 1.0f, 0.0f, 0.0f);
glrotatef（yrot, 0.0f, 1.0f, 0.0f);
// get supported point size range and step size
glgetfloatv（gl_point_size_range,sizes);
glgetfloatv（gl_point_size_granularity,&step);
// set the initial point size
cursize = sizes[0];
// set beginning z coordinate
z = -50.0f;
// loop around in a circle three times
for（angle = 0.0f; angle <= （2.0f*3.1415f)*3.0f; angle += 0.1f)
{
// calculate x and y values on the circle
// specify the point size before the primative is specified
glpointsize（cursize);
x = 50.0f*sin（angle);
y = 50.0f*cos（angle);
// draw the point
glbegin（gl_points);
glvertex3f（x, y, z);
glend（);
z += 0.5f;
cursize += step;
// bump up the z value and the point size
}
// restore matrix state
glpopmatrix（);
// flush drawing commands
glutswapbuffers（);
}
// this function does any needed initialization on the rendering
// context.
void setuprc（)
{
// black background
glclearcolor（0.0f, 0.0f, 0.0f, 1.0f );
// set drawing color to green
glcolor3f（0.0f, 1.0f, 0.0f);
}
void specialkeys（int key, int x, int y)
{
if（key == glut_key_up)
xrot-= 5.0f;
if（key == glut_key_down)
xrot += 5.0f;
if（key == glut_key_left)
yrot -= 5.0f;
if（key == glut_key_right)
yrot += 5.0f;
if（key > 356.0f)
xrot = 0.0f;
if（key < -1.0f)
xrot = 355.0f;
if（key > 356.0f)
yrot = 0.0f;
if（key < -1.0f)
yrot = 355.0f;
// refresh the window
glutpostredisplay（);
}
void changesize（int w, int h)
{
glfloat nrange = 100.0f;
// prevent a divide by zero
if（h == 0)
h = 1;
// set viewport to window dimensions
glviewport（0, 0, w, h);
// reset projection matrix stack
glmatrixmode（gl_projection);
glloadidentity（);
// establish clipping volume （left, right, bottom, top, near, far)
if （w <= h)
glortho （-nrange, nrange, -nrange*h/w, nrange*h/w, -nrange, nrange);
else
glortho （-nrange*w/h, nrange*w/h, -nrange, nrange, -nrange, nrange);
// reset model view matrix stack
glmatrixmode（gl_modelview);
glloadidentity（);
}
int main（int argc, char* argv[])
{
glutinit（&argc, argv);
glutinitdisplaymode（glut_double ¦ glut_rgb ¦ glut_depth);
glutcreatewindow（"points size example");
glutreshapefunc（changesize);
glutspecialfunc（specialkeys);
glutdisplayfunc（renderscene);
setuprc（);
glutmainloop（);
return 0;
}
|
|
|
|
|
