所谓顶点缓冲就是直接将顶点数据存储在gpu的一段缓冲区，不需要从cpu拷贝到gpu。提高了程序的运行效率。
操作步骤
1.创建顶点缓冲对象
GLuint vertexBufferID;
2.分配空间
glGenBuffers(1, &vertexBufferID);
3.绑定当前顶点缓冲对象
glBindBuffer(GL_ARRAY_BUFFER, vertexBufferID);
4.初始化缓冲区数据
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
5.启用顶点属性数组
glEnableVertexAttribArray(GLKVertexAttribPosition);
6.使用顶点数据进行渲染
glVertexAttribPointer(
GLKVertexAttribPosition,
3,
GL_FLOAT,
GL_FALSE,
sizeof(SceneVertex),
NULL);
7.绘制
glDrawArrays(GL_TRIANGLES, 0,3);
下面赋全部代码
@interface OpenGLESViewController : GLKViewController
{
GLuint vertexBufferID;
}
@property (strong, nonatomic) GLKBaseEffect *baseEffect;
@end
#import "OpenGLESViewController.h"
@implementation OpenGLESViewController
@synthesize baseEffect;
/////////////////////////////////////////////////////////////////
// This data type is used to store information for each vertex
typedef struct {
GLKVector3 positionCoords;
}
SceneVertex;
// Define vertex data for a triangle to use in example
static const SceneVertex vertices[] =
{
{{-0.5f, -0.5f, 0.0}}, // lower left corner
{{ 0.5f, -0.5f, 0.0}}, // lower right corner
{{-0.5f, 0.5f, 0.0}} // upper left corner
};
/////////////////////////////////////////////////////////////////
// Called when the view controller's view is loaded
// Perform initialization before the view is asked to draw
- (void)viewDidLoad
{
[super viewDidLoad];
// Verify the type of view created automatically by the
// Interface Builder storyboard
GLKView *view = (GLKView *)self.view;
NSAssert([view isKindOfClass:[GLKView class]],
@"View controller's view is not a GLKView");
// Create an OpenGL ES 2.0 context and provide it to the
// view
view.context = [[EAGLContext alloc]
initWithAPI:kEAGLRenderingAPIOpenGLES2];
// Make the new context current
[EAGLContext setCurrentContext:view.context];
// Create a base effect that provides standard OpenGL ES 2.0
// Shading Language programs and set constants to be used for
// all subsequent rendering
self.baseEffect = [[GLKBaseEffect alloc] init];
self.baseEffect.useConstantColor = GL_TRUE;
self.baseEffect.constantColor = GLKVector4Make(
1.0f, // Red
1.0f, // Green
1.0f, // Blue
1.0f);// Alpha
// Set the background color stored in the current context
glClearColor(0.0f, 0.0f, 0.0f, 1.0f); // background color
// Generate, bind, and initialize contents of a buffer to be
// stored in GPU memory
glGenBuffers(1, // STEP 1
&vertexBufferID);
glBindBuffer(GL_ARRAY_BUFFER, // STEP 2
vertexBufferID);
glBufferData( // STEP 3
GL_ARRAY_BUFFER, // Initialize buffer contents
sizeof(vertices), // Number of bytes to copy
vertices, // Address of bytes to copy
GL_STATIC_DRAW); // Hint: cache in GPU memory
}
/////////////////////////////////////////////////////////////////
// GLKView delegate method: Called by the view controller's view
// whenever Cocoa Touch asks the view controller's view to
// draw itself. (In this case, render into a frame buffer that
// shares memory with a Core Animation Layer)
- (void)glkView:(GLKView *)view drawInRect:(CGRect)rect
{
[self.baseEffect prepareToDraw];
// Clear Frame Buffer (erase previous drawing)
glClear(GL_COLOR_BUFFER_BIT);
// Enable use of positions from bound vertex buffer
glEnableVertexAttribArray( // STEP 4
GLKVertexAttribPosition);
glVertexAttribPointer( // STEP 5
GLKVertexAttribPosition,
3, // three components per vertex
GL_FLOAT, // data is floating point
GL_FALSE, // no fixed point scaling
sizeof(SceneVertex), // no gaps in data
NULL); // NULL tells GPU to start at
// beginning of bound buffer
// Draw triangles using the first three vertices in the
// currently bound vertex buffer
glDrawArrays(GL_TRIANGLES, // STEP 6
0, // Start with first vertex in currently bound buffer
3); // Use three vertices from currently bound buffer
}