objective-c – OpenGL ES 1.1顶点缓冲区对象不起作用

我正在使用OpenGL ES 1.1开发iPhone游戏,并且需要使用顶点缓冲对象来渲染500个粒子而不会降低性能.

我的游戏能够使用非VBO方法成功绘制,但现在我已经尝试合并VBO,没有任何东西可以绘制了.

请帮助我确定我做错了什么,并提供一个正确的例子.

我有一个名为TexturedQuad的类,它包含以下内容：

// TexturedQuad.h

enum {
    ATTRIB_POSITION,ATTRIB_TEXTURE_COORD
 };

@interface TexturedQuad : NSObject {

    GLfloat *textureCoords; // 8 elements for 4 points (u and v)
    GLfloat *vertices;      // 8 elements for 4 points (x and y)
    GLubyte *indices;       // how many elements does this need?

    // vertex buffer array IDs generated using glGenBuffers(..)
    GLuint vertexBufferID;
    GLuint textureCoordBufferID;
    GLuint indexBufferID;

    // ...other ivars
}

// @synthesize in .m file for each property
@property (nonatomic,readwrite) GLfloat *textureCoords;
@property (nonatomic,readwrite) GLfloat *vertices;
@property (nonatomic,readwrite) GLubyte *indices;
@property (nonatomic,readwrite) GLuint vertexBufferID;
@property (nonatomic,readwrite) GLuint textureCoordBufferID;
@property (nonatomic,readwrite) GLuint indexBufferID;

// vertex buffer object methods
- (void) createVertexBuffers;
- (void) createTextureCoordBuffers;
- (void) createIndexBuffer;

在TexturedQuad.m中,创建了顶点缓冲区：

- (void) createVertexBuffers {
    glGenBuffers(1,&vertexBufferID);
    glBindBuffer(GL_ARRAY_BUFFER,vertexBufferID);
    glBufferData(GL_ARRAY_BUFFER,sizeof(vertices),vertices,GL_STATIC_DRAW);
}

- (void) createTextureCoordBuffers {
    glGenBuffers(1,&textureCoordBufferID);
    glBindBuffer(GL_ARRAY_BUFFER,textureCoordBufferID);
    glBufferData(GL_ARRAY_BUFFER,sizeof(textureCoords),textureCoords,GL_STATIC_DRAW);
}

- (void) createIndexBuffer {
    glGenBuffers(1,&indexBufferID);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,indexBufferID);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER,sizeof(GLubyte) * 16,indices,GL_STATIC_DRAW);
}

上述VBO创建方法由自定义AtlasLibrary类调用,该类初始化每个TexturedQuad实例.

首先,顶点按以下格式排列：

// bottom left
quad.vertices[0] = xMin;
quad.vertices[1] = yMin;

// bottom right
quad.vertices[2] = xMax;
quad.vertices[3] = yMin;

// top left
quad.vertices[4] = xMin;
quad.vertices[5] = yMax;

// top right
quad.vertices[6] = xMax;
quad.vertices[7] = yMax;

其次,纹理坐标按以下格式排列(翻转以考虑OpenGL ES镜像图像的倾向)：

// top left (of texture)
quad.textureCoords[0] = uMin;
quad.textureCoords[1] = vMax;

// top right
quad.textureCoords[2] = uMax;
quad.textureCoords[3] = vMax;

// bottom left
quad.textureCoords[4] = uMin;
quad.textureCoords[5] = vMin;

// bottom right
quad.textureCoords[6] = uMax;
quad.textureCoords[7] = vMin;

…接下来,调用VBO创建方法(在AtlasLibrary中)

[quad createVertexBuffers];
[quad createTextureCoordBuffers];
[quad createIndexBuffer];

现在的肉和土豆. SceneObject类. SceneObjects是游戏中可渲染的对象.它们引用TexturedQuad实例并包含有关旋转,平移和缩放的信息.

这是SceneObject中的render方法：

- (void) render {

    // binds texture in OpenGL ES if not already bound
    [[AtlasLibrary sharedAtlasLibrary] ensureContainingTextureAtlasIsBoundInOpenGLES:self.containingAtlasKey];

    glPushMatrix();

    glTranslatef(translation.x,translation.y,translation.z);

    glRotatef(rotation.x,1,0);
    glRotatef(rotation.y,0);
    glRotatef(rotation.z,1);

    glScalef(scale.x,scale.y,scale.z);

    // change alpha
    glColor4f(1.0,1.0,alpha);

    // vertices
    glBindBuffer(GL_ARRAY_BUFFER,texturedQuad.vertexBufferID);
    glVertexAttribPointer(ATTRIB_POSITION,2,GL_FLOAT,GL_FALSE,sizeof(GL_FLOAT),&texturedQuad.vertices[0]);


    // texture coords
    glBindBuffer(GL_ARRAY_BUFFER,texturedQuad.textureCoordBufferID);
    glVertexAttribPointer(ATTRIB_TEXTURE_COORD,&texturedQuad.textureCoords[0]);

    // bind index buffer array
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,texturedQuad.indexBufferID);

    // draw
    glDrawElements(GL_TRIANGLE_STRIP,sizeof(texturedQuad.indices) / sizeof(texturedQuad.indices[0]),GL_UNSIGNED_BYTE,texturedQuad.indices);

    glPopMatrix();
}

我有一种强烈的感觉,我的索引数组结构不正确或glDrawElements(..)函数调用不正确.

要回答这个问题,请：

>识别我正在做的错误会导致OpenGL ES不能绘制我的SceneObjects.
>提供正确的方法来做我想做的事情(请根据我的框架)
>提供任何可能有用的建议或链接(可选)

非常感谢！

解决方法

我对OpenGL和OpenGL ES之间的差异没有经验,但我没有在你的代码中看到任何对 glEnableVertexAttribArray()的调用.

该功能在OpenGL ES 1.1 docs中可疑缺失,但是在2.0,并且正在Apple’s OpenGL ES VBO article中使用(感谢JSPerfUnkn0wn).

以下是Vertex Buffer Objects和Index Buffer Objects上的一些其他优秀(但非ES)教程.