我尝试使用求值器在 OpenGL 中使用 C++ 制作小型波发生器。
但是，由于我的评估器仅部分点亮，因此我运气不佳。
为什么会这样？
为了完整起见，下面我包含了完整的源代码，您可能只需要查看 init()、display() 和顶部的常量的文件。
#include <gl/glui.h>
#include <math.h>
const int DIMX = 500;
const int DIMY = 500;
const int INITIALPOS_X = 200;
const int INITIALPOS_Y = 200;
// Aspect ratio (calculated on the fly)
float xy_aspect;
// UI aux. matrices
float view_rotate[16] = { 1,0,0,0,
0,1,0,0,
0,0,1,0,
0,0,0,1 };
float obj_pos[] = { 0.0, 0.0, 0.0 };
float obj_pan[] = { 0.0, 0.0, 0.0 };
// Referential axis
double axis_radius_begin = 0.2;
double axis_radius_end = 0.0;
double axis_lenght = 16.0;
int axis_nslices = 8;
int axis_nstacks = 1;
// Light 0 properties
float light0_position[] = {5.0, 5.0, 5.0, 0.0};
float light0_ambient[] = {0.0, 0.0, 0.0, 1.0};
float light0_diffuse[] = {0.6, 0.6, 0.6, 1.0};
float light0_specular[] = {1.0, 1.0, 1.0, 1.0};
float light0_kc = 0.0;
float light0_kl = 1.0;
float light0_kq = 0.0;
double light0x = 5.0;
double light0y = 5.0;
double light0z = 5.0;
double symb_light0_radius = 0.2;
int symb_light0_slices = 8;
int symb_light0_stacks =8;
// Ambient light source properties
float light_ambient[] = {0.5, 0.5, 0.5, 1.0}; /* Set the background ambient lighting. */
// Windowing related variables
int main_window;
GLUquadric* glQ;
GLUI *glui;
const unsigned int gridSize = 40;
float grid[gridSize][gridSize][3];
const int uSize = gridSize;
const int vSize = gridSize;
GLfloat ambient[] = {0.2, 0.2, 0.2, 1.0};
GLfloat position[] = {0.0, 0.0, 2.0, 1.0};
GLfloat mat_diffuse[] = {0.6, 0.6, 0.6, 1.0};
GLfloat mat_specular[] = {1.0, 1.0, 1.0, 1.0};
float mat_shininess[] = {50.0};
void display(void) {
static float value = 0;
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode( GL_PROJECTION );
glLoadIdentity();
glFrustum( -xy_aspect*.04, xy_aspect*.04, -.04, .04, .1, 50.0 );
glMatrixMode( GL_MODELVIEW );
glLoadIdentity();
glTranslatef( obj_pos[0], obj_pos[1], -obj_pos[2]-25 );
glTranslatef( obj_pan[0], obj_pan[1], obj_pan[2] );
glRotated( 20.0, 1.0,0.0,0.0 );
glRotated(-45.0, 0.0,1.0,0.0 );
glMultMatrixf( view_rotate );
glColorMaterial(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE);
glEnable(GL_COLOR_MATERIAL);
glColor3f(1.0,0.0,0.0);
glPushMatrix();
glRotated(90.0, 0.0,1.0,0.0 );
gluCylinder(glQ, axis_radius_begin, axis_radius_end,
axis_lenght, axis_nslices, axis_nstacks);
glPopMatrix();
glColor3f(0.0,1.0,0.0);
glPushMatrix();
glRotated(-90.0, 1.0,0.0,0.0 );
gluCylinder(glQ, axis_radius_begin, axis_radius_end,
axis_lenght, axis_nslices, axis_nstacks);
glPopMatrix();
glColor3f(0.0,0.0,1.0);
glPushMatrix();
gluCylinder(glQ, axis_radius_begin, axis_radius_end,
axis_lenght, axis_nslices, axis_nstacks);
glPopMatrix();
light0_position[0] = light0x;
light0_position[1] = light0y;
light0_position[2] = light0z;
glLightfv(GL_LIGHT0, GL_POSITION, light0_position);
glColor3f(1.0,1.0,0.0);
gluQuadricOrientation( glQ, GLU_INSIDE);
glPushMatrix();
glTranslated(light0x,light0y,light0z);
gluSphere(glQ, symb_light0_radius, symb_light0_slices, symb_light0_stacks);
glPopMatrix();
gluQuadricOrientation( glQ, GLU_OUTSIDE);
gluQuadricDrawStyle(glQ, GLU_FILL);
gluQuadricNormals(glQ, GLU_SMOOTH);
gluQuadricOrientation(glQ, GLU_OUTSIDE);
gluQuadricTexture(glQ, GL_FALSE);
for (unsigned int y = 0; y < vSize; ++y) {
for (unsigned int x = 0; x < uSize; ++x) {
float xVal = 5*3.14/gridSize*x;
float yVal = 5*3.14/gridSize*y;
grid[y][x][0] = (float) x/gridSize*10.0;
grid[y][x][1] = sin(xVal + value) + sin(yVal + value);
grid[y][x][2] = (float) y/gridSize*10.0;
}
}
glMap2f(GL_MAP2_VERTEX_3, 0, 1 , 3, uSize, 0, 1, uSize * 3, vSize, &grid[0][0][0]);
glEvalMesh2(GL_FILL, 0, gridSize, 0, gridSize);
value += 3.14/25;
if (value > 3.14*2)
value = 0;
// swapping the buffers causes the rendering above to be shown
glutSwapBuffers();
glFlush();
}
/* Mouse handling */
void processMouse(int button, int state, int x, int y)
{
if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN)
{
}
if (button == GLUT_RIGHT_BUTTON && state == GLUT_DOWN)
{
}
glutPostRedisplay();
}
void processMouseMoved(int x, int y)
{
// pedido de refrescamento da janela
glutPostRedisplay();
}
void processPassiveMouseMoved(int x, int y)
{
// pedido de refrescamento da janela
glutPostRedisplay();
}
void reshape(int w, int h)
{
int tx, ty, tw, th;
GLUI_Master.get_viewport_area( &tx, &ty, &tw, &th );
glViewport( tx, ty, tw, th );
xy_aspect = (float)tw / (float)th;
glutPostRedisplay();
}
void keyboard(unsigned char key, int x, int y)
{
switch (key) {
case 27: // tecla de escape termina o programa
exit(0);
break;
}
}
void glut_idle( void )
{
if ( glutGetWindow() != main_window )
glutSetWindow(main_window);
glutPostRedisplay();
}
void init()
{
glQ = gluNewQuadric();
glFrontFace(GL_CCW); // Front faces defined using a counterclockwise rotation
glDepthFunc(GL_LEQUAL); // Por defeito e GL_LESS
glEnable(GL_DEPTH_TEST); // Use a depth (z) buffer to draw only visible objects
glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);
glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess);
// Face Culling para aumentar a velocidade
glEnable(GL_CULL_FACE);
glCullFace(GL_BACK); // GL_FRONT, GL_BACK, GL_FRONT_AND_BACK
// Define que modelo de iluminacao utilizar; consultar o manual de referencia
glLightModelfv(GL_LIGHT_MODEL_AMBIENT, light_ambient); // define luz ambiente
glLightModelf (GL_LIGHT_MODEL_TWO_SIDE, GL_FALSE);
glLightModeli (GL_LIGHT_MODEL_LOCAL_VIEWER, 1);
// por defeito a cor de fundo e o preto
// glClearColor(1.0,1.0,1.0,1.0); // cor de fundo a branco
// declaracoes para a fonte luz GL_LIGHT0
glLightfv(GL_LIGHT0, GL_AMBIENT, light0_ambient);
glLightfv(GL_LIGHT0, GL_DIFFUSE, light0_diffuse);
glLightfv(GL_LIGHT0, GL_SPECULAR, light0_specular);
glLightf(GL_LIGHT0, GL_CONSTANT_ATTENUATION, light0_kc);
glLightf(GL_LIGHT0, GL_LINEAR_ATTENUATION, light0_kl);
glLightf(GL_LIGHT0, GL_QUADRATIC_ATTENUATION, light0_kq);
// NOTA: a direccao e a posicao de GL_LIGHT0 estao na rotina display(), pelo
// que as isntrucoes seguntes nao sao necessarias
//glLightf(GL_LIGHT0, GL_SPOT_CUTOFF, 90.0);
//glLightfv(GL_LIGHT0, GL_SPOT_DIRECTION, spot_direction);
//glLightfv(GL_LIGHT0, GL_POSITION, light0_position);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glEnable(GL_NORMALIZE);
glEnable(GL_MAP2_VERTEX_3);
glMapGrid2f(gridSize, 0.0, 1.0, gridSize, 0.0, 1.0);
glShadeModel(GL_SMOOTH);
glPolygonMode(GL_FRONT, GL_FILL);
//glPolygonMode(GL_FRONT, GL_LINE);
}
void do_nothing(int key, int x, int y) {}
int main(int argc, char* argv[])
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
glutInitWindowSize (DIMX, DIMY);
glutInitWindowPosition (INITIALPOS_X, INITIALPOS_Y);
main_window = glutCreateWindow (argv[0]);
glutDisplayFunc(display);
GLUI_Master.set_glutReshapeFunc(reshape);
GLUI_Master.set_glutKeyboardFunc (keyboard);
GLUI_Master.set_glutMouseFunc(processMouse);
glutMotionFunc(processMouseMoved);
glutPassiveMotionFunc(processPassiveMouseMoved);
GLUI_Master.set_glutSpecialFunc( do_nothing );
/*** Create the bottom subwindow ***/
glui = GLUI_Master.create_glui_subwindow( main_window, GLUI_SUBWINDOW_BOTTOM );
glui->set_main_gfx_window( main_window );
GLUI_Rotation *view_rot = glui->add_rotation( "Rotation", view_rotate );
view_rot->set_spin( 1.0 );
glui->add_column( false );
GLUI_Translation *trans_z = glui->add_translation( "Zoom", GLUI_TRANSLATION_Z, &obj_pos[2] );
trans_z->set_speed( .1 );
glui->add_column(false);
GLUI_Translation *trans_pan = glui->add_translation("Pan", GLUI_TRANSLATION_XY, &obj_pan[0]);
trans_pan->set_speed(.1);
GLUI_Master.set_glutIdleFunc( glut_idle );
init();
glutMainLoop();
return 0;
}
最佳答案
您说 OpenGL 求值器不需要设置法线。这只是部分正确。如果您通过调用为评估器启用自动生成的法线，则不需要设置法线:
glEnable(GL_AUTO_NORMAL);
仅仅启用 GL_NORMALIZE 是不行的。
但是您当然也可以通过为 GL_MAP2_NORMAL 提供控制点来指定您自己的法线，就像为 GL_MAP2_VERTEX_3 一样。
如果不提及 OpenGL 求值器已被高度弃用并且很可能由驱动程序在软件中实现，则答案是不完整的。因此，滚动您自己的 Bezier 评估代码(这不是很难)并生成绘制为 GL_TRIANGLES 的简单网格肯定是一个更好的主意。
关于c++ - OpenGL 评估器仅部分点亮，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/8175620/