[toc]
前言
通过前面的纹理一系列学习,针对一个案例对所学知识进行综合应用.
首先看效果图.
image.png
按下前后键有种穿越隧道的效果.
使用不同的Mip纹理贴图模式
首先,将隧道分为四部分,地面,天花板,左面和右面墙面.由看图可知,只需要加载三张tga文件,左右一样.
- 首先,创建
4个批次类容器,分别存放四个面,有效果可知,只需要在z轴移动,初始化一个z轴的深度值,通过宏定义对纹理加上表示符号用来区分.
//4个批次容器类
GLBatch floorBatch;//地面
GLBatch ceilingBatch;//天花板
GLBatch leftWallBatch;//左墙面
GLBatch rightWallBatch;//右墙面
//深度初始值，-65。
GLfloat viewZ = -65.0f;
// 纹理标识符号
#define TEXTURE_BRICK 0 //墙面
#define TEXTURE_FLOOR 1 //地板
#define TEXTURE_CEILING 2 //纹理天花板
#define TEXTURE_COUNT 3 //纹理个数
// tag文件名数组保存
GLuint textures[TEXTURE_COUNT];//纹理标记数组
//文件tag名字数组
const char *szTextureFiles[TEXTURE_COUNT] = { "brick.tga", "floor.tga", "ceiling.tga" };
- 接着,在
SetupRC中,创建纹理对象,读取tga文件(读取像素),设置过滤方式和环绕模式,最后载入纹理.
void SetupRC()
{
...
//纹理对象
glGenTextures(TEXTURE_COUNT, textures);
//通过数组加载
for(iLoop = 0; iLoop < TEXTURE_COUNT; iLoop++)
{
//绑定纹理
glBindTexture(GL_TEXTURE_2D, textures[iLoop]);
//读取像素
pBytes = gltReadTGABits(szTextureFiles[iLoop],&iWidth, &iHeight,
&iComponents, &eFormat);
//过滤方式
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
//环绕方式
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
//载入纹理
glTexImage2D(GL_TEXTURE_2D, 0, iComponents, iWidth, iHeight, 0, eFormat, GL_UNSIGNED_BYTE, pBytes);
//Mipmap
glGenerateMipmap(GL_TEXTURE_2D);
//释放
free(pBytes);
}
...
}
- 接下来绘制纹理坐标和顶点坐标(上,下,左,右),建立几何图形
1. 地板
image.png
对应顶点和纹理坐标
floorBatch.Begin(GL_TRIANGLE_STRIP, 28, 1);
for(z = 60.0f; z >= 0.0f; z -=10.0f)
{
floorBatch.MultiTexCoord2f(0, 0.0f, 0.0f);
floorBatch.Vertex3f(-10.0f, -10.0f, z);
floorBatch.MultiTexCoord2f(0, 1.0f, 0.0f);
floorBatch.Vertex3f(10.0f, -10.0f, z);
floorBatch.MultiTexCoord2f(0, 0.0f, 1.0f);
floorBatch.Vertex3f(-10.0f, -10.0f, z - 10.0f);
floorBatch.MultiTexCoord2f(0, 1.0f, 1.0f);
floorBatch.Vertex3f(10.0f, -10.0f, z - 10.0f);
}
floorBatch.End();
2. 天花板
image.png
对应顶点和纹理坐标
ceilingBatch.Begin(GL_TRIANGLE_STRIP, 28, 1);
for(z = 60.0f; z >= 0.0f; z -=10.0f)
{
ceilingBatch.MultiTexCoord2f(0, 0.0f, 1.0f);
ceilingBatch.Vertex3f(-10.0f, 10.0f, z - 10.0f);
ceilingBatch.MultiTexCoord2f(0, 1.0f, 1.0f);
ceilingBatch.Vertex3f(10.0f, 10.0f, z - 10.0f);
ceilingBatch.MultiTexCoord2f(0, 0.0f, 0.0f);
ceilingBatch.Vertex3f(-10.0f, 10.0f, z);
ceilingBatch.MultiTexCoord2f(0, 1.0f, 0.0f);
ceilingBatch.Vertex3f(10.0f, 10.0f, z);
}
ceilingBatch.End();
3.左边墙
image.png
对应顶点坐标和纹理坐标
leftWallBatch.Begin(GL_TRIANGLE_STRIP, 28, 1);
for(z = 60.0f; z >= 0.0f; z -=10.0f)
{
leftWallBatch.MultiTexCoord2f(0, 0.0f, 0.0f);
leftWallBatch.Vertex3f(-10.0f, -10.0f, z);
leftWallBatch.MultiTexCoord2f(0, 0.0f, 1.0f);
leftWallBatch.Vertex3f(-10.0f, 10.0f, z);
leftWallBatch.MultiTexCoord2f(0, 1.0f, 0.0f);
leftWallBatch.Vertex3f(-10.0f, -10.0f, z - 10.0f);
leftWallBatch.MultiTexCoord2f(0, 1.0f, 1.0f);
leftWallBatch.Vertex3f(-10.0f, 10.0f, z - 10.0f);
}
leftWallBatch.End();
```
**4.右边墙**
[图片上传失败...(image-c6d39e-1595383726768)]
对应顶点和坐标
```swift
rightWallBatch.Begin(GL_TRIANGLE_STRIP, 28, 1);
for(z = 60.0f; z >= 0.0f; z -=10.0f)
{
rightWallBatch.MultiTexCoord2f(0, 0.0f, 0.0f);
rightWallBatch.Vertex3f(10.0f, -10.0f, z);
rightWallBatch.MultiTexCoord2f(0, 0.0f, 1.0f);
rightWallBatch.Vertex3f(10.0f, 10.0f, z);
rightWallBatch.MultiTexCoord2f(0, 1.0f, 0.0f);
rightWallBatch.Vertex3f(10.0f, -10.0f, z - 10.0f);
rightWallBatch.MultiTexCoord2f(0, 1.0f, 1.0f);
rightWallBatch.Vertex3f(10.0f, 10.0f, z - 10.0f);
}
rightWallBatch.End();
-
在
RenderScene设置平移矩阵和图形和纹理绘制- 只在z轴方向移动,压入一个
Translate矩阵 - 纹理替换矩阵着色器进行批次类提交
- 最后绑定纹理绘制
- 只在z轴方向移动,压入一个
void RenderScene(void)
{
...
//压入一个z轴方向平移矩阵
modelViewMatrix.PushMatrix();
modelViewMatrix.Translate(0.0f, 0.0f, viewZ);
// 纹理替换矩阵着色器shaderManager.UseStockShader(GLT_SHADER_TEXTURE_REPLACE, transformPipeline.GetModelViewProjectionMatrix(), 0);
//绑定纹理
glBindTexture(GL_TEXTURE_2D, textures[TEXTURE_FLOOR]);
floorBatch.Draw();
glBindTexture(GL_TEXTURE_2D, textures[TEXTURE_CEILING]);
ceilingBatch.Draw();
glBindTexture(GL_TEXTURE_2D, textures[TEXTURE_BRICK]);
leftWallBatch.Draw();
rightWallBatch.Draw();
modelViewMatrix.PopMatrix();
...
}
- 添加菜单入口改变过滤器
int main(int argc, char *argv[])
{
// 添加菜单入口，改变过滤器
glutCreateMenu(ProcessMenu);
glutAddMenuEntry("GL_NEAREST",0);
glutAddMenuEntry("GL_LINEAR",1);
glutAddMenuEntry("GL_NEAREST_MIPMAP_NEAREST",2);
glutAddMenuEntry("GL_NEAREST_MIPMAP_LINEAR", 3);
glutAddMenuEntry("GL_LINEAR_MIPMAP_NEAREST", 4);
glutAddMenuEntry("GL_LINEAR_MIPMAP_LINEAR", 5);
glutAddMenuEntry("Anisotropic Filter", 6);
glutAddMenuEntry("Anisotropic Off", 7);
glutAttachMenu(GLUT_RIGHT_BUTTON);
}
-
ProcessMenu函数,每次改变选择都重新绑定,在设置过滤
void ProcessMenu(int value)
{
GLint iLoop;
for(iLoop = 0; iLoop < TEXTURE_COUNT; iLoop++)
{
/**绑定纹理 glBindTexture
参数1：GL_TEXTURE_2D
参数2：需要绑定的纹理对象
*/
glBindTexture(GL_TEXTURE_2D, textures[iLoop]);
/**配置纹理参数 glTexParameteri
参数1：纹理模式
参数2：纹理参数
参数3：特定纹理参数
*/
switch(value)
{
case 0:
//GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER(缩小过滤器)，GL_NEAREST（最邻近过滤）
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
break;
case 1:
//GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER(缩小过滤器)，GL_LINEAR（线性过滤）
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
break;
case 2:
//GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER(缩小过滤器)，GL_NEAREST_MIPMAP_NEAREST（选择最邻近的Mip层，并执行最邻近过滤）
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST_MIPMAP_NEAREST);
break;
case 3:
//GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER(缩小过滤器)，GL_NEAREST_MIPMAP_LINEAR（在Mip层之间执行线性插补，并执行最邻近过滤）
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST_MIPMAP_LINEAR);
break;
case 4:
//GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER(缩小过滤器)，GL_NEAREST_MIPMAP_LINEAR（选择最邻近Mip层，并执行线性过滤）
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST);
break;
case 5:
//GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER(缩小过滤器)，GL_LINEAR_MIPMAP_LINEAR（在Mip层之间执行线性插补，并执行线性过滤，又称为三线性过滤）
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
break;
case 6:
//设置各向异性过滤
GLfloat fLargest;
//获取各向异性过滤的最大数量
glGetFloatv(GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT, &fLargest);
//设置纹理参数(各向异性采样)
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, fLargest);
break;
case 7:
//设置各向同性过滤，数量为1.0表示(各向同性采样)
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, 1.0f);
break;
}
}
//触发重画
glutPostRedisplay();
}
效果图:
image.png
image.png
