#100317#NeHe学习笔记---添加纹理

最新推荐文章于 2025-07-07 16:27:53 发布

原创最新推荐文章于 2025-07-07 16:27:53 发布 · 320 阅读

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文章标签：

#file #image #initialization #textures #buffer #generation

本文详细介绍了如何在OpenGL中加载并使用纹理，包括定义纹理变量、读取图像文件、生成纹理及设置纹理映射参数等步骤。通过具体的代码示例展示了整个流程。

首先是在框架中添加了几个变量：
GLfloat xrot;
GLfloat yrot;
GLfloat zrot;
GLuint texture[1];     //用于存储纹理的数据结构

然后添加了一个用于读取图像的函数：
AUX_RGBImageRec *LoadBMP(char *Filename) // Loads A Bitmap Image
{
FILE *File=NULL; // File Handle

if (!Filename) // Make Sure A Filename Was Given
{
return NULL; // If Not Return NULL
}

File=fopen(Filename,"r"); // Check To See If The File Exists

if (File)           // Does The File Exist?
{
  fclose(File);         // Close The Handle
  return auxDIBImageLoad(Filename);    // Load The Bitmap And Return A Pointer
}

return NULL; // If Load Failed Return NULL
}

又添加了一个用于装载纹理的函数：

int LoadGLTextures() // Load Bitmaps And Convert To Textures
{
int Status=FALSE; // Status Indicator

AUX_RGBImageRec *TextureImage[1]; // Create Storage Space For The Texture

memset(TextureImage,0,sizeof(void *)*1); // Set The Pointer To NULL

// Load The Bitmap, Check For Errors, If Bitmap's Not Found Quit
if (TextureImage[0]=LoadBMP("Data/NeHe.bmp"))
{
Status=TRUE; // Set The Status To TRUE

glGenTextures(1, &texture[0]); // Create The Texture

  // Typical Texture Generation Using Data From The Bitmap
  glBindTexture(GL_TEXTURE_2D, texture[0]);
  glTexImage2D(GL_TEXTURE_2D, 0, 3, TextureImage[0]->sizeX, TextureImage[0]->sizeY, 0, GL_RGB, GL_UNSIGNED_BYTE, TextureImage[0]->data);
  glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
  glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
}

if (TextureImage[0])         // If Texture Exists
{
  if (TextureImage[0]->data)       // If Texture Image Exists
  {
   free(TextureImage[0]->data);     // Free The Texture Image Memory
  }

free(TextureImage[0]); // Free The Image Structure
}

return Status; // Return The Status
}

即是如何用图像生成纹理的。

再修改int InitGL(GLvoid)函数，使纹理设置生效：

      int InitGL(GLvoid)          // All Setup For OpenGL Goes Here
{
if (!LoadGLTextures())        // Jump To Texture Loading Routine ( NEW )
{
  return FALSE;         // If Texture Didn't Load Return FALSE
}

glEnable(GL_TEXTURE_2D);       // Enable Texture Mapping ( NEW )
glShadeModel(GL_SMOOTH);       // Enable Smooth Shading
glClearColor(0.0f, 0.0f, 0.0f, 0.5f);    // Black Background
glClearDepth(1.0f);         // Depth Buffer Setup
glEnable(GL_DEPTH_TEST);       // Enables Depth Testing
glDepthFunc(GL_LEQUAL);        // The Type Of Depth Testing To Do
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); // Really Nice Perspective Calculations
return TRUE;          // Initialization Went OK
}

最后

int DrawGLScene(GLvoid) // Here's Where We Do All The Drawing
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear The Screen And The Depth Buffer
glLoadIdentity(); // Reset The View
glTranslatef(0.0f,0.0f,-5.0f);

glRotatef(xrot,1.0f,0.0f,0.0f);
glRotatef(yrot,0.0f,1.0f,0.0f);
glRotatef(zrot,0.0f,0.0f,1.0f);

glBindTexture(GL_TEXTURE_2D, texture[0]); //？？可选，注释后运行无障碍。

glBegin(GL_QUADS);
  // Front Face
  glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f);
  glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f);
  glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 1.0f);
  glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 1.0f);
  // Back Face
  glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f);
  glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, 1.0f, -1.0f);
  glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, 1.0f, -1.0f);
  glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f);
  // Top Face
  glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, -1.0f);
  glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, 1.0f, 1.0f);
  glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, 1.0f, 1.0f);
  glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, -1.0f);
  // Bottom Face
  glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, -1.0f, -1.0f);
  glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, -1.0f, -1.0f);
  glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f);
  glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f);
  // Right face
  glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f);
  glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, -1.0f);
  glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 1.0f);
  glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f);
  // Left Face
  glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f);
  glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f);
  glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 1.0f);
  glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, -1.0f);
glEnd();

xrot+=0.3f;
yrot+=0.2f;
zrot+=0.4f;
return TRUE; // Keep Going
}

（0.0f，0.0f）是左下的坐标，其余的类似设置来改变纹理的方向。