OpenGL(七)-纹理(下)

绘制一个隧道

定义绘制批次类

GLShaderManager     shaderManager;          //着色器管理器
GLMatrixStack       modelViewMatrix;        //模型视图矩阵
GLMatrixStack       projectionMatrix;       //投影矩阵
GLFrustum           viewFrustum;            //视景体
GLGeometryTransform transformPipeline;      //几何变换管线

//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
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" };

初始化

floor.png
ceiling.png
leftWall.png
rightWall.png

//在这个函数里能够在渲染环境中进行任何需要的初始化，它这里的设置并初始化纹理对象
void SetupRC()
{
    GLbyte *pBytes;
    GLint iWidth,iHeight,iComponents;
    GLenum eFormat;
    GLint iLoop;
    
    //背景
    glClearColor(0.0f, 0.0f, 0.0f,1.0f);
    
    shaderManager.InitializeStockShaders();
    
    //1.加载纹理
    /*
     glGenTextures (GLsizei n, GLuint *textures)
     参数1:n,纹理数量
     参数2:textures,纹理对象标识数组
     */
    glGenTextures(TEXTURE_COUNT, textures);
    
    for (iLoop =0; iLoop < TEXTURE_COUNT; iLoop++) {
        
        //2.绑定纹理
        /*
         glBindTexture (GLenum target, GLuint texture);
         参数1:target,使用的纹理类型GL_TEXTURE_1D\GL_TEXTURE_2D\GL_TEXTURE_3D
         参数2:texture,纹理的标记
         */

        glBindTexture(GL_TEXTURE_2D, textures[iLoop]);
        
        
        //3.加载tga文件
        /*
         GLbyte *gltReadTGABits(const char *szFileName, GLint *iWidth, GLint *iHeight, GLint *iComponents, GLenum *eFormat, GLbyte *pData);
         参数1:szFileName 纹理文件的名称
         参数2:iWidth 获取纹理文件的宽度
         参数3:iHeight获取纹理文件的高度
         参数4:iComponents获取纹理文件的组件
         参数5:eFormat获取纹理文件的格式
         
         返回值:指向图像数据的指针
         */
        pBytes = gltReadTGABits(szTextureFiles[iLoop], &iWidth, &iHeight, &iComponents, &eFormat);
        
        //放大过滤器
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
        //缩小过滤器
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
        //环绕方式--S
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
        //环绕方式--T
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
        
        
        //载入纹理
        /*
          glTexImage2D (GLenum target, GLint level, GLint internalformat, GLsizei width, GLsizei height, GLint border, GLenum format, GLenum type, const GLvoid *pixels);
         参数1:target,使用的纹理类型GL_TEXTURE_1D\GL_TEXTURE_2D\GL_TEXTURE_3D
         参数2:level ,Mip贴图的层次
         参数3:internalformat,纹理单元的颜色组成方式(从读取像素图中获得)
         参数4:width
         参数5:height
         参数6:border 
         参数7:format 
         参数8:type,像素数据的数据类型-GL_UNSIGNED_BYTE
         参数9:pixels,指向纹理图像数据的指针
         */
        glTexImage2D(GL_TEXTURE_2D, 0, iComponents, iWidth, iHeight, 0, eFormat, GL_UNSIGNED_BYTE, pBytes);
        
        //生成MIP图层
        /*
          参数1:GL_TEXTURE_1D\GL_TEXTURE_2D\GL_TEXTURE_3D
         */
        glGenerateMipmap(GL_TEXTURE_2D);
        
        free(pBytes);
        
    }
    
    
    //建立立体图像!!!
    GLfloat z;
    
    /*
       void Begin(GLenum primitive, GLuint nVerts, GLuint nTextureUnits = 0);
     参数1:绘图模式
     参数2:顶点个数
     参数3:纹理,默认等于0
     */
    floorBatch.Begin(GL_TRIANGLE_STRIP, 28,1);//共绘制了7个四边形, 共28个顶点
    
    //参考图 - floor.png
    for (z = 60.0f; z >= 0.0f; z -= 10.0f) {
        
        //指定顶点对应纹理的坐标
        floorBatch.MultiTexCoord2f(0, 0, 0);
        //指定左下角顶点
        floorBatch.Vertex3f(-10.0f, -10.0f, z);
        
        
        //指定右下角顶点以及纹理坐标
        floorBatch.MultiTexCoord2f(0, 1, 0);
        floorBatch.Vertex3f(10.0f, -10.0f, z);
        
        
        //指定顶点对应纹理的坐标
        floorBatch.MultiTexCoord2f(0, 0, 1.0f);
        floorBatch.Vertex3f(-10.0f, -10.0f, z-10.0f);
        
        
        //指定顶点对应纹理的坐标
        floorBatch.MultiTexCoord2f(0, 1.0f, 1.0f);
        floorBatch.Vertex3f(10.0f, -10.0f, z-10.0f);
        
  
    }
    
    floorBatch.End();
    
    //参考图- ceiling.png
    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();
    
    //参考图 - leftWall.png
    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();
    
    //参考图 - rightWall.png
    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();

}

窗口设置

//改变视景体和视口，在改变窗口大小或初始化窗口调用
void ChangeSize(int w, int h)
{
    if (h == 0) {
        
        h = 1;
    }
    
    glViewport(0, 0, w, h);
    
    //透视投影纵横比
    GLfloat fAspect;
    fAspect = (GLfloat)w / (GLfloat)h;
    
    //设置透视投影
    viewFrustum.SetPerspective(80.0f, fAspect, 1.0, 120.0);
    
    //获取到投影矩阵
    projectionMatrix.LoadMatrix(viewFrustum.GetProjectionMatrix());
    
    //通过变换管线来管理投影矩阵堆栈
    transformPipeline.SetMatrixStacks(modelViewMatrix, projectionMatrix);
    
}

调用，绘制场景

void RenderScene(void)
{
    glClear(GL_COLOR_BUFFER_BIT);
    
    modelViewMatrix.PushMatrix();
    
    modelViewMatrix.Translate(0.0f, 0.0f, viewZ);
    
    //纹理替换矩阵着色器
    /*
     参数1:GLT_SHADER_TEXTURE_REPLACE
     参数2:模型视图矩阵 & 投影矩阵
     参数3:纹理层次
     */
    shaderManager.UseStockShader(GLT_SHADER_TEXTURE_REPLACE,transformPipeline.GetModelViewProjectionMatrix(),0);
    
    //地板
    glBindTexture(GL_TEXTURE_2D, textures[TEXTURE_FLOOR]);
    floorBatch.Draw();
    
    //天花板
    glBindTexture(GL_TEXTURE_2D, textures[TEXTURE_CEILING]);
    ceilingBatch.Draw();
    
    //左右墙壁
    glBindTexture(GL_TEXTURE_2D, textures[TEXTURE_BRICK]);
    leftWallBatch.Draw();
    rightWallBatch.Draw();
    
    modelViewMatrix.PopMatrix();
    
    glutSwapBuffers();
    
    
    
}

效果图

image.png