我正在处理背景纹理。我想要做的是我想要设置背景图像。为了在我的代码中我使用切换到ortho，绘制一个充满窗口大小的正方形，纹理它。然后切换回3d并绘制3D图像。它绘制背景纹理和雪人，但它们都会在一秒钟内消失。我不知道错误代码在哪里。我认为必须与推动和弹出矩阵有关。下面是我的InitGl，draw（）和drawnowman（），main和reshape（）的代码。我认为问题是在3D到2d之间的swithc期间的draw（）函数。建议？
int main (int argc, char **argv)
{
glutInit (&argc, argv);
glutInitDisplayMode (GLUT_DOUBLE);
glutInitWindowSize (500, 500);
glutInitWindowPosition (100, 100);
glutCreateWindow ("A basic OpenGL Window");
glutKeyboardFunc(key);
if( !initGL() ) { // NEW (16)
printf( "Unable to initialize graphics library!\n" );
return 1;
}
glutDisplayFunc (display);
// glutIdleFunc (display);
glutIdleFunc(idle);
glutReshapeFunc (reshape);
//Load our texture
texture = LoadTexture( "texture.bmp", 256, 256 );
glutMainLoop ();
//Free our texture
FreeTexture( texture );
return 0;
}
void drawSnowMan(void)
{
GLUquadricObj *pObj;
//glDisable(GL_TEXTURE_2D);
glEnable(GL_CULL_FACE);
glCullFace(GL_BACK);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LESS);
// save the world matrix
glPushMatrix();
glTranslatef(xpos, -0.5, -5.0);
glRotated(rotX,1,0,0); // ******** NEW (11)
glRotated(rotY,0,1,0);
pObj = gluNewQuadric();
gluQuadricNormals(pObj, GLU_SMOOTH);
//glRotated(rotZ,0,0,1);
glPushMatrix();
//setting up light effect for base, mid and head spheres. all red!
ambient[0] = 1.0; ambient[1] = 0.0; ambient[2] = 0.0;
diffuse[0] = 1.0; diffuse[1] = 0.0; diffuse[2] = 0.0;
specular[0] = 0.7; specular[1] = 0.6; specular[2] = 0.5;
glMaterialfv(GL_FRONT, GL_AMBIENT, ambient);
glMaterialfv(GL_FRONT, GL_DIFFUSE, diffuse);
glMaterialfv(GL_FRONT, GL_SPECULAR, specular);
glMaterialfv(GL_FRONT, GL_SHININESS, shiness);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
//glTranslatef(0.0 ,0.75f, 0.0f);
//bottom sphere. dont need to gltranslate again because it will use the previous gltranslate
//which is declared outside
glutSolidSphere(0.70f,20,20);
//mid sphere
glTranslatef(0.0f, 1.0f, 0.0f);
glutSolidSphere(0.45f,20,20);
//top sphere
glTranslatef(0.0f, 0.6f, 0.0f);
glutSolidSphere(0.30f,20,20);
//eyes
glDisable(GL_LIGHTING);
glDisable(GL_LIGHT0);
glPopMatrix();
//drawing hat
glPushMatrix();
//black color. move it 1.85 in y position because thats where the head is
//rotate the cylinder and draw cylinder
glColor3f(0.0f, 0.0f, 0.0f);
glTranslatef(0.0f, 1.85f, 0.0f);
glRotatef(-90.0f, 1.0f, 0.0f, 0.0f);
gluCylinder(pObj, 0.17f, 0.17f, 0.4f, 26, 13);
//drawing brim. disable cull_face. draw disk, so front part. disabl
glDisable(GL_CULL_FACE);
gluDisk(pObj, 0.17f, 0.28f, 26, 13);
glEnable(GL_CULL_FACE);
glTranslatef(0.0f, 0.0f, 0.40f);
gluDisk(pObj, 0.17f, 0.28f, 26, 13);
glPopMatrix();
glPushMatrix();
glPushMatrix();
glColor3f(1.0,1.0,1.0);
glTranslatef(2.0f, 1.0f, 0.0f);
glRotatef(90.0,0.0, 0.0,-5.0);
glScalef (0.01, 0.2, 0.06); /* modeling transformation */
//glutSolidCone(0.1, 0.1, 10.0, 14.0);
glutSolidCube(1.5);
glPopMatrix();
glPushMatrix();
glTranslatef(2.0f, 0.8f, 0.0f);
glRotatef(-90.0f, 1.0f, 0.0f, 0.0f);
gluCylinder(pObj, 0.04f, 0.04f, 0.2f, 26, 13);
glPopMatrix();
//blade
glPushMatrix();
ambient[0] = 0.0; ambient[1] = 1.0; ambient[2] = 0.0;
diffuse[0] = 1.0; diffuse[1] = 0.0; diffuse[2] = 0.0;
specular[0] = 0.7; specular[1] = 0.6; specular[2] = 0.5;
glMaterialfv(GL_FRONT, GL_AMBIENT, ambient);
glMaterialfv(GL_FRONT, GL_DIFFUSE, diffuse);
glMaterialfv(GL_FRONT, GL_SPECULAR, specular);
glMaterialfv(GL_FRONT, GL_SHININESS, shiness);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT1);
glTranslatef(2.0f, 1.0f, 0.0f);
glRotatef(-90.0f, 1.0f, 0.0f, 0.0f);
gluCylinder(pObj, 0.03f, 0.03f, 1.1f, 26, 13);
glDisable(GL_LIGHTING);
glDisable(GL_LIGHT0);
glPopMatrix();
glPopMatrix();
//big push matrix for eyes, and nose
glPushMatrix();
//eyes color = black light. set defuse all 0, ambient = black. turns the eyes black
/*ambient[0] = 0.0; ambient[1] = 0.0; ambient[2] = 0.0;
diffuse[0] = 0.0; diffuse[1] = 0.0; diffuse[2] = 0.0;
specular[0] = 0.7; specular[1] = 0.6; specular[2] = 0.5;
glMaterialfv(GL_FRONT, GL_AMBIENT, ambient);
glMaterialfv(GL_FRONT, GL_DIFFUSE, diffuse);
glMaterialfv(GL_FRONT, GL_SPECULAR, specular);
glMaterialfv(GL_FRONT, GL_SHININESS, shiness);*/
glColor3f(0.0, 0.0, 0.0);
//left eye
glPushMatrix();
glTranslatef(-0.17, 1.7, 0.25 );
glutSolidSphere(0.05, 10.0, 10.0);
glPopMatrix();
//right eye
glPushMatrix();
glTranslatef(0.17, 1.7, 0.25 );
glutSolidSphere(0.05, 10.0, 10.0);
glPopMatrix();
//drawing nose
glPushMatrix();
glTranslatef(0.0, 1.6, 0.25 );
glutSolidCone(0.08f,0.5f,10,2);
glPopMatrix();
glPopMatrix(); // end big push matrix for eyes and nose
glPopMatrix();
} // end of drawsnowman()
void display (void) {
glClearColor(0.25f, 0.25f, 0.50f, 1.0f ); // blueish color
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// glLoadIdentity();
// MODEL VIEW is set up in IniitGL
//so save it
glPushMatrix();
//switch to projection matrix
//swithc to ortho.
//draw texture
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.0, 1.0, 0.0, 1.0, 0.0, -1.0);
glDisable(GL_DEPTH_TEST);
glDisable(GL_LIGHTING);
glDepthMask(GL_FALSE);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, texture);
// Draw a textured quad
glBegin(GL_QUADS);
glTexCoord2f(0, 0); glVertex3f(0, 0, 0);
glTexCoord2f(0, 1); glVertex3f(0, 1, 0);
glTexCoord2f(1, 1); glVertex3f(1, 1, 0);
glTexCoord2f(1, 0); glVertex3f(1, 0, 0);
glEnd();
glDepthMask(GL_TRUE);
glEnable(GL_DEPTH_TEST);
glPopMatrix();// pop the 3d model view
glMatrixMode(GL_PROJECTION);
glMatrixMode(GL_MODELVIEW);
// You can ignore this. just a different of way drawing texture and still does not work
/* glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
glOrtho(0.0, 1.0, 0.0, 1.0, 0.0, -1.0);
glDisable(GL_DEPTH_TEST);
glDisable(GL_LIGHTING);
glDepthMask(GL_FALSE);
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glDepthMask( false );
glLoadIdentity();
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, texture);
// Draw a textured quad
glBegin(GL_QUADS);
glTexCoord2f(0, 0); glVertex3f(0, 0, 0);
glTexCoord2f(0, 1); glVertex3f(0, 1, 0);
glTexCoord2f(1, 1); glVertex3f(1, 1, 0);
glTexCoord2f(1, 0); glVertex3f(1, 0, 0);
glEnd();
glDepthMask(GL_TRUE);
glEnable(GL_DEPTH_TEST);
glEnable(GL_LIGHTING);
/*glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective (60, 800 / 600, 1.0, 100.0);;
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt( 0.0, 0.0, 0.0, // Where would the camera be?
0.0, 0.0,-1.0, // Where would it be looking?
0.0, 1.0, 0.0); // What would be the "up" vector?fa*/
/* glDisable(GL_TEXTURE_2D);
glPopMatrix();
glMatrixMode(GL_PROJECTION);
glPopMatrix();
//gluPerspective (45, SCREEN_WIDTH / SCREEN_HEIGHT, 1.0, 100.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();*/
drawSnowMan(); // draw snow man
glutSwapBuffers();
angle ++;
}
void reshape (int w, int h) {
glViewport (0, 0, (GLsizei)w, (GLsizei)h);
glMatrixMode (GL_PROJECTION);
glLoadIdentity ();
gluPerspective (45, (GLfloat)w / (GLfloat)h, 1.0, 100.0);
glMatrixMode (GL_MODELVIEW);
}
bool initGL (void) {
glViewport(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT);
// Switch to the "camera" mode
glMatrixMode(GL_PROJECTION); // Camera
glLoadIdentity();
// Change the camera to a 3D view
glFrustum( -1 * (float) SCREEN_WIDTH / SCREEN_HEIGHT,
(float) SCREEN_WIDTH / SCREEN_HEIGHT,
-1.0,
1.0,
1.5,
1000.0);
glClearColor(0.25f, 0.25f, 0.50f, 1.0f );
glHint(GL_LINE_SMOOTH_HINT, GL_NICEST); // NEW (5)
glEnable(GL_LINE_SMOOTH); // NEW (6)
glHint(GL_POLYGON_SMOOTH_HINT, GL_NICEST); // NEW (7)
glEnable(GL_POLYGON_SMOOTH); // NEW (8)
// this is a specular light
GLfloat mat_specular[] = { 1.0 , 1.0 , 1.0 , 1.0 }; // Color of a "shiny material
GLfloat mat_shininess[] = { 50.0 }; // How shiny is it?
// GLfloat mat_ambient_and_diffuse[] = { 0.0, 1.0, 0.0, 1.0 };
GLfloat light_position[] = { 1.0, 1.0, 1.0, 0.0 }; // Infinitely far away. Direction light
GLfloat light_position1[] = {2.0,1.5,0.0,1.0}; // saber light
// How to calculate the surface normal for pixels
glShadeModel(GL_SMOOTH); // Try this as well GL_FLAT
// Setup up some material reflective properties
// glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
// glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess);
//glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient_and_diffuse);
//glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_ambient_and_diffuse);
// Finally actually make the light
glLightfv(GL_LIGHT0, GL_POSITION, light_position);
glLightfv(GL_LIGHT1, GL_POSITION, light_position1);
//Check for error
GLenum error = glGetError(); // NEW (9)
if( error != GL_NO_ERROR ) {
printf( "Error initializing OpenGL! %s\n", gluErrorString( error ) );
return false;
}
return true;
}
void idle(void) {
glutPostRedisplay();
}
答案 0 :(得分：1)
重新认识新手误解：OpenGL“初始化”。
OpenGL 未初始化！您在 initGL 和重塑中的所有代码都属于显示。
在调用 glLight ... 的情况下，在将模型视图矩阵设置到您希望灯光所在的空间中后，将必须放置在显示中。此外，OpenGL是不是库;是的，最初OpenGL中的'L'确实意味着库，但我将它回溯到 Layer ，因为它就是大多数现代图形系统的原因：最终用户程序与GPU及其驱动程序之间的层
我认为一旦您将代码从 initGL 和重塑移动到 display ，解决方案应该变得清晰：您可以更改，重置和随时修改投影和模型视图矩阵。要使显示中的窗口宽度和高度可以将它们存储在 reshape 中的全局变量中，或者首选解决方案，请使用glutGet(GLUT_WINDOW_WIDTH)和glutGet(GLUT_WINDOW_HEIGHT)来查询窗口尺寸。显示功能。
你想在正投影中绘制东西吗？然后适当地设置投影和模型视图。切换到一个角度？就这么做。
答案 1 :(得分：0)
我想我有点弄清楚为什么我的背景纹理会不断消失。我有Cullface和深度的东西打开。我把它关掉了弹出最后一个矩阵然后就可以了。
然而，有一个问题。纹理图像是雪背景，但它变成全红色。所以首先我认为这是由于snowgirl照明的反射。我关掉了所有的灯，仍然是红色的。无法弄清楚为什么。可能是，纹理颜色与雪人的原始颜色融为一体吗？