opengl - 如何将纹理应用于 glutSolidCube

Question

我可以找到有关将纹理映射到多边形指定顶点等的教程，但没有关于如何将纹理应用于使用 glut (glutSolidCube) 绘制的立方体(或其他东西)的教程。

我正在做类似的事情:

glTexEnvfv(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, decal);
glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, repeat);
glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, repeat);
glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, nearest);
glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, nearest);

glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glTexImage2D(GL_TEXTURE_2D, 0, 4, myImageWidth, myImageHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, (GLvoid *)myImage);

//...

glEnable(GL_TEXTURE_2D);

//now draw the cube
glutSolidCube(N);

这样做我将纹理应用于立方体，但整个立方体获得纹理中第一个字节的颜色!

使用 glutSolidCube 时，有没有办法将纹理映射到实体立方体(和其他实体)？

Answer 1

不，因为 glutSolidCube()不生成纹理坐标。幸运的是，glutSolidCube()很容易自己实现并添加纹理坐标。这是glutSolidCube()的源代码和相关函数，来自 http://www.opengl.org/resources/libraries/glut/ :

/* Copyright (c) Mark J. Kilgard, 1994, 1997. */

/**                                                                             
(c) Copyright 1993, Silicon Graphics, Inc.                                      

ALL RIGHTS RESERVED                                                             

Permission to use, copy, modify, and distribute this software                   
for any purpose and without fee is hereby granted, provided                     
that the above copyright notice appear in all copies and that                   
both the copyright notice and this permission notice appear in                  
supporting documentation, and that the name of Silicon                          
Graphics, Inc. not be used in advertising or publicity                          
pertaining to distribution of the software without specific,                    
written prior permission.

THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU
"AS-IS" AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR
OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL SILICON GRAPHICS, INC.  BE LIABLE TO YOU OR ANYONE
ELSE FOR ANY DIRECT, SPECIAL, INCIDENTAL, INDIRECT OR
CONSEQUENTIAL DAMAGES OF ANY KIND, OR ANY DAMAGES WHATSOEVER,
INCLUDING WITHOUT LIMITATION, LOSS OF PROFIT, LOSS OF USE,
SAVINGS OR REVENUE, OR THE CLAIMS OF THIRD PARTIES, WHETHER OR
NOT SILICON GRAPHICS, INC.  HAS BEEN ADVISED OF THE POSSIBILITY
OF SUCH LOSS, HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
ARISING OUT OF OR IN CONNECTION WITH THE POSSESSION, USE OR
PERFORMANCE OF THIS SOFTWARE.

US Government Users Restricted Rights

Use, duplication, or disclosure by the Government is subject to
restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
(c)(1)(ii) of the Rights in Technical Data and Computer
Software clause at DFARS 252.227-7013 and/or in similar or
successor clauses in the FAR or the DOD or NASA FAR
Supplement.  Unpublished-- rights reserved under the copyright
laws of the United States.  Contractor/manufacturer is Silicon
Graphics, Inc., 2011 N.  Shoreline Blvd., Mountain View, CA
94039-7311.

OpenGL(TM) is a trademark of Silicon Graphics, Inc.
*/

static void
drawBox(GLfloat size, GLenum type)
{
  static GLfloat n[6][3] =
  {
    {-1.0, 0.0, 0.0},
    {0.0, 1.0, 0.0},
    {1.0, 0.0, 0.0},
    {0.0, -1.0, 0.0},
    {0.0, 0.0, 1.0},
    {0.0, 0.0, -1.0}
  };
  static GLint faces[6][4] =
  {
    {0, 1, 2, 3},
    {3, 2, 6, 7},
    {7, 6, 5, 4},
    {4, 5, 1, 0},
    {5, 6, 2, 1},
    {7, 4, 0, 3}
  };
  GLfloat v[8][3];
  GLint i;

  v[0][0] = v[1][0] = v[2][0] = v[3][0] = -size / 2;
  v[4][0] = v[5][0] = v[6][0] = v[7][0] = size / 2;
  v[0][1] = v[1][1] = v[4][1] = v[5][1] = -size / 2;
  v[2][1] = v[3][1] = v[6][1] = v[7][1] = size / 2;
  v[0][2] = v[3][2] = v[4][2] = v[7][2] = -size / 2;
  v[1][2] = v[2][2] = v[5][2] = v[6][2] = size / 2;

  for (i = 5; i >= 0; i--) {
    glBegin(type);
    glNormal3fv(&n[i][0]);
    glVertex3fv(&v[faces[i][0]][0]);
    glVertex3fv(&v[faces[i][1]][0]);
    glVertex3fv(&v[faces[i][2]][0]);
    glVertex3fv(&v[faces[i][3]][0]);
    glEnd();
  }
}

void APIENTRY
glutSolidCube(GLdouble size)
{
  drawBox(size, GL_QUADS);
}

只需添加一些调用 glTexCoord*函数族。 NeHe有一个关于如何开始使用 OpenGL 进行纹理映射的好教程。