下面的代码围绕它们的局部轴旋转金字塔和立方体（我相信）。为什么使用此代码两个对象都会变亮和变暗？当然，光会来自一个固定的位置（如太阳），而物体本身不会完全变暗变亮吗？
是什么导致了这种行为？这是旧的即时模式。我是 OpenGL 新手。
看起来光源被“粘合”到每个物体的表面上。当每个物体旋转时，它的光源也会随之旋转。
#include <windows.h> // Header File For Windows
#include <gl\gl.h> // Header File For The OpenGL32 Library
#include <gl\glu.h> // Header File For The GLu32 Library
#include <GL\glut.h>
static void resize(int width, int height)
{
const float ar = (float) width / (float) height;
glViewport(0, 0, width, height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glFrustum(-ar, ar, -1.0, 1.0, 2.0, 100.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity() ;
}
GLfloat rtri = 0.0; // Angle For The Triangle
GLfloat rquad = 0.0; // Angle For The Quad
GLfloat xPosCube = 0.0;
//--------------------------------------------------------------------------------------------
// DrawPyramid
//--------------------------------------------------------------------------------------------
void DrawPyramid( void )
{
glLoadIdentity();
glTranslatef( -1.5f, 0.0f, -6.0f ); // Move Left 1.5 Units And Into The Screen 6.0
glRotatef( rtri, 0.0f, 1.0f, 0.0f ); // Rotate The Triangle On The Y axis
glBegin( GL_TRIANGLES ); // Start Drawing The Pyramid
// Face 1
glVertex3f( 0.0f, 1.0f, 0.0f ); // Top Of Triangle (Front)
glVertex3f( -1.0f, -1.0f, 1.0f ); // Left Of Triangle (Front)
glVertex3f( 1.0f, -1.0f, 1.0f ); // Right Of Triangle (Front)
// Face 2
glVertex3f( 0.0f, 1.0f, 0.0f); // Top Of Triangle (Right)
glVertex3f( 1.0f,-1.0f, 1.0f); // Left Of Triangle (Right)
glVertex3f( 1.0f,-1.0f, -1.0f); // Right Of Triangle (Right)
// Face 3
glVertex3f( 0.0f, 1.0f, 0.0f); // Top Of Triangle (Back)
glVertex3f( 1.0f,-1.0f, -1.0f); // Left Of Triangle (Back)
glVertex3f(-1.0f,-1.0f, -1.0f); // Right Of Triangle (Back)
// Face 4
glVertex3f( 0.0f, 1.0f, 0.0f); // Top Of Triangle (Left)
glVertex3f(-1.0f,-1.0f,-1.0f); // Left Of Triangle (Left)
glVertex3f(-1.0f,-1.0f, 1.0f); // Right Of Triangle (Left)
glEnd();
}
//--------------------------------------------------------------------------------------------
// DrawCube
//--------------------------------------------------------------------------------------------
void DrawCube( void )
{
glLoadIdentity();
glTranslatef( 1.75f /* + xPosCube*/ ,0.0f,-7.0f + xPosCube); // Move Right And Into The Screen
glRotatef(rquad,1.0f,1.0f,1.0f); // Rotate The Cube On X, Y & Z
glBegin(GL_QUADS);
glVertex3f( 1.0f, 1.0f,-1.0f); // Top Right Of The Quad (Top)
glVertex3f(-1.0f, 1.0f,-1.0f); // Top Left Of The Quad (Top)
glVertex3f(-1.0f, 1.0f, 1.0f); // Bottom Left Of The Quad (Top)
glVertex3f( 1.0f, 1.0f, 1.0f); // Bottom Right Of The Quad (Top)
glVertex3f( 1.0f,-1.0f, 1.0f); // Top Right Of The Quad (Bottom)
glVertex3f(-1.0f,-1.0f, 1.0f); // Top Left Of The Quad (Bottom)
glVertex3f(-1.0f,-1.0f,-1.0f); // Bottom Left Of The Quad (Bottom)
glVertex3f( 1.0f,-1.0f,-1.0f); // Bottom Right Of The Quad (Bottom)
glVertex3f( 1.0f, 1.0f, 1.0f); // Top Right Of The Quad (Front)
glVertex3f(-1.0f, 1.0f, 1.0f); // Top Left Of The Quad (Front)
glVertex3f(-1.0f,-1.0f, 1.0f); // Bottom Left Of The Quad (Front)
glVertex3f( 1.0f,-1.0f, 1.0f); // Bottom Right Of The Quad (Front)
glVertex3f( 1.0f,-1.0f,-1.0f); // Bottom Left Of The Quad (Back)
glVertex3f(-1.0f,-1.0f,-1.0f); // Bottom Right Of The Quad (Back)
glVertex3f(-1.0f, 1.0f,-1.0f); // Top Right Of The Quad (Back)
glVertex3f( 1.0f, 1.0f,-1.0f); // Top Left Of The Quad (Back)
glVertex3f(-1.0f, 1.0f, 1.0f); // Top Right Of The Quad (Left)
glVertex3f(-1.0f, 1.0f,-1.0f); // Top Left Of The Quad (Left)
glVertex3f(-1.0f,-1.0f,-1.0f); // Bottom Left Of The Quad (Left)
glVertex3f(-1.0f,-1.0f, 1.0f); // Bottom Right Of The Quad (Left)
glVertex3f( 1.0f, 1.0f,-1.0f); // Top Right Of The Quad (Right)
glVertex3f( 1.0f, 1.0f, 1.0f); // Top Left Of The Quad (Right)
glVertex3f( 1.0f,-1.0f, 1.0f); // Bottom Left Of The Quad (Right)
glVertex3f( 1.0f,-1.0f,-1.0f); // Bottom Right Of The Quad (Right)
glEnd(); // Done Drawing The Quad
}
//--------------------------------------------------------------------------------------------
// DrawPyramidHiddenLinesPolygonOffset()
//--------------------------------------------------------------------------------------------
void DrawPyramidHiddenLinesPolygonOffset( void )
{
// Draw cube - Hidden Line Removal with Polygon Offset..
glEnable(GL_DEPTH_TEST);
glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
glColor4f(1.0f,0.0f,0.0f, 1.0f); // Set The Color To Violet
DrawPyramid();
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
glEnable(GL_POLYGON_OFFSET_FILL);
glPolygonOffset(1.0, 1.0);
glColor4f(0.5f,0.0f,0.0f, 0.1f); // Set The Color To Violet
DrawPyramid();
glDisable(GL_POLYGON_OFFSET_FILL);
}
//--------------------------------------------------------------------------------------------
// DrawCubeHiddenLinesPolygonOffset()
//--------------------------------------------------------------------------------------------
void DrawCubeHiddenLinesPolygonOffset( void )
{
// Draw cube - Hidden Line Removal with Polygon Offset..
glEnable(GL_DEPTH_TEST);
glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
glColor4f(1.0f,0.0f,1.0f, 1.0f); // Set The Color To Violet
DrawCube( FALSE );
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
glEnable(GL_POLYGON_OFFSET_FILL);
glPolygonOffset(1.0, 1.0);
glColor4f(0.5f,0.0f,0.5f, 0.1f); // Set The Color To Violet
DrawCube( FALSE );
glDisable(GL_POLYGON_OFFSET_FILL);
}
//--------------------------------------------------------------------------------------------
// DrawGLScene()
//--------------------------------------------------------------------------------------------
void DrawGLScene(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// Do camera rotation first..
// Now draw and rotate objects..
DrawCubeHiddenLinesPolygonOffset();
DrawPyramidHiddenLinesPolygonOffset();
rtri += 0.022f; // Increase The Rotation Variable For The Triangle
rquad -= 0.045f; // Decrease The Rotation Variable For The Quad
//xPosCube -= 0.0005f;
glutSwapBuffers();
}
const GLfloat light_ambient[] = { 0.0f, 0.0f, 0.0f, 1.0f };
const GLfloat light_diffuse[] = { 1.0f, 1.0f, 1.0f, 1.0f };
const GLfloat light_specular[] = { 1.0f, 1.0f, 1.0f, 1.0f };
const GLfloat light_position[] = { 2.0f, 5.0f, 5.0f, 0.0f };
const GLfloat mat_ambient[] = { 0.7f, 0.7f, 0.7f, 1.0f };
const GLfloat mat_diffuse[] = { 0.8f, 0.8f, 0.8f, 1.0f };
const GLfloat mat_specular[] = { 1.0f, 1.0f, 1.0f, 1.0f };
const GLfloat high_shininess[] = { 100.0f };
void IdleFunc()
{
glutPostRedisplay();
}
void KeyboardFunc( BYTE key, int x, int y )
{
switch (key)
{
case 27: // Escape key
//glutDestroyWindow( Win.id );
exit (0);
break;
}
}
/* Program entry point */
int main(int argc, char *argv[])
{
glutInit(&argc, argv);
glutInitWindowSize(640,480);
glutInitWindowPosition(10,10);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
glutCreateWindow("Programming Techniques - 3D Spheres");
glutKeyboardFunc( KeyboardFunc );
glutReshapeFunc(resize);
glutDisplayFunc( DrawGLScene );
glutIdleFunc( IdleFunc );
glClearColor(1,1,1,1);
glEnable(GL_CULL_FACE);
glCullFace(GL_BACK);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LESS);
glEnable(GL_LIGHT0);
glEnable(GL_NORMALIZE);
glEnable(GL_COLOR_MATERIAL);
glEnable(GL_LIGHTING);
glLightfv(GL_LIGHT0, GL_AMBIENT, light_ambient);
glLightfv(GL_LIGHT0, GL_DIFFUSE, light_diffuse);
glLightfv(GL_LIGHT0, GL_SPECULAR, light_specular);
glLightfv(GL_LIGHT0, GL_POSITION, light_position);
glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient);
glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);
glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
glMaterialfv(GL_FRONT, GL_SHININESS, high_shininess);
glutMainLoop();
return EXIT_SUCCESS;
}