OpenGL ES GLKit(二)

A, GLKit Framework Overview

• GLKit framework designed to simplify the development of applications based on OpenGL / OpenGL ES's. It appears
  to accelerate OpenGL ES or OpenGL development of the applications. Use math library, background texture loading, pre-created with
  color filter effects, as well as the standard view and the view controller to achieve rendering loop.
• GLKit framework provides functions and classes required can be reduced to create a new application based shader work,
  or a fixed support existing vertex or fragment processing function dependent on an earlier version of the OpenGL ES or OpenGL provides
  an application.
• Draw spaces provided GLKView (View)
• GLKViewController (UIKit extensions to the standard design pattern for managing drawing view content and presentation)
• Apple abandoned OpenGL ES, but iOS developers can continue to use.

Second, the use GLKit view render OpenGL ES content

GLKit view showing OpenGL ES content .png

Third, the configuration view GLKit

- (void)viewDidLoad{ 
    [super viewDidLoad];
    //创建OpenGL ES上下文并将其分配给从故事板加载的视图
    GLKView * view =(GLKView *)self.view;
    view.context = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];
    //配置视图创建的渲染缓冲区
    view.drawableColorFormat = GLKViewDrawableColorFormatRGBA8888;
    view.drawableDepthFormat = GLKViewDrawableDepthFormat24;
    view.drawableStencilFormat = GLKViewDrawableStencilFormat8;
    //启⽤多重采样
    view.drawableMultisample = GLKViewDrawableMultisample4X;
}

-(void)drawRect:(CGRect)rect
{
    //清除帧缓冲区
    glClearColor(0.0f，0.0f，0.1f，1.0f); 
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    //使用先前配置的纹理，着色器和顶点数组绘制 
    glBindTexture(GL_TEXTURE_2D，_planetTexture); 
    glUseProgram(_diffuseShading);     
    glUniformMatrix4fv(_uniformModelViewProjectionMatrix，1,0，_modelViewProjectionMatrix.m); 
    glBindVertexArrayOES(_planetMesh); 
    glDrawElements(GL_TRIANGLE_STRIP，256，GL_UNSIGNED_SHORT);
}

Four, GLKit function

• Load textures
• ADVANCED providing performance math
• It provides constant ⻅ shaders
• And a controller provides a view of view.

Five, GLKit texture load

1. GLKTextureInfo create OpenGL texture information

• name: OpenGL texture context name
• target: target texture bound
• height: loading textures and altitudes
• width: Width of the loaded textures
• textureOrigin: Load the texture of the origin position
• alphaState: loading state texture alpha component
• containsMipmaps: Boolean value that contains loads of texture mip map

2. GLTextureLoader simplified load textures from a variety of resource file

• initialization

  • initWithSharegroup: initialize a new texture loaded into an object
  • initWithShareContext: Initialization causes a new texture loading objects

• Load processing from a file

  • +textureWithContentsOfFile:options:errer: 从文件加载2D纹理图像并从数据中创建新的纹理
  • -textureWithContentsOfFile:options:queue:completionHandler: 从⽂件中异步加载2D纹理图像,并根据数据创建新纹理

• 从URL加载纹理

  • -textureWithContentsOfURL:options:error: 从URL加载2D纹理图像并从数据创建新纹理
  • -textureWithContentsOfURL:options:queue:completionHandler: 从URL异步加载2D纹理图像,并根据数据创建新纹理

• 从内存中表示创建纹理

  • +textureWithContentsOfData:options:errer: 从内存空间加载2D纹理图像,并根据数据创建新纹理
  • -textureWithContentsOfData:options:queue:completionHandler:从内存空间异步加载2D纹理图像,并从数据中创建新纹理

• 从CGImages创建纹理

  • -textureWithCGImage:options:error: 从Quartz图像加载2D纹理图像并从数据创建新纹理
  • -textureWithCGImage:options:queue:completionHandler: 从Quartz图像异步加载2D纹理图像,并根据数据创建新纹理

• 从URL加载多维创建纹理

  • +cabeMapWithContentsOfURL:options:errer: 从单个URL加载立方体贴图纹理图像,并根据数据创建新纹理
  • -cabeMapWithContentsOfURL:options:queue:completionHandler:从单个URL异步加载立方体贴图纹理图像,并根据数据创建新纹理

• 从文件加载多维数据创建纹理

  • +cubeMapWithContentsOfFile:options:errer: 从单个⽂件加载立⽅体贴图纹理对象,并从数据中创建新纹理
  • -cubeMapWithContentsOfFile:options:queue:completionHandler:从单个文件异步加载⽴方体贴图纹理对象,并从数据中创建新纹理
  • +cubeMapWithContentsOfFiles:options:errer: 从⼀系列文件中加载立方体贴图纹理图像,并从数据总创建新纹理
  • -cubeMapWithContentsOfFiles:options:options:queue:completionHandler:从一系列文件异步加载⽴方体贴图纹理图像,并从数据中创建新纹理

六、GLKit OpenGL ES 视图渲染

1. GLKView 使⽤OpenGL ES 绘制内容的视图默认实现

• 初始化视图

  • -initWithFrame:context: 初始化新视图

• 代理

  • delegate 视图的代理

• 配置帧缓存区对象

  • drawableColorFormat 颜色渲染缓存区格式
  • drawableDepthFormat 深度渲染缓存区格式
  • drawableStencilFormat 模板渲染缓存区的格式
  • drawableMultisample 多重采样缓存区的格式

• 帧缓存区属性

  • drawableHeight 底层缓存区对象的高度(以像素为单位)
  • drawableWidth 底层缓存区对象的宽度(以像素为单位)

• 绘制视图的内容

  • context 绘制视图内容时使⽤的OpenGL ES 上下文
  • -bindDrawable 将底层FrameBuffer 对象绑定到OpenGL ES
  • enableSetNeedsDisplay 布尔值,指定视图是否响应使得视图内容无效的消息
  • -display 立即重绘视图内容
  • snapshot 绘制视图内容并将其作为新图像对象返回

• 删除视图FrameBuffer对象

  • -deleteDrawable 删除与视图关联的可绘制对象

2. GLKViewDelegate ⽤于GLKView 对象回调方法

• 绘制视图的内容
  • -glkView:drawInRect: 绘制视图内容 (必须实现代理)

3. GLKViewController 管理OpenGL ES 渲染循环的视图控制器

• 更新

  • -(void)update 更新视图内容
  • -(void)glkViewControllerUpdate:

• 配置帧速率

  • preferredFramesPerSecond 视图控制器调用视图以及更新视图内容的速率
  • framesPerSencond 视图控制器调用视图以及更新其内容的实际速率

• 配置GLKViewController 代理

  • delegate 视图控制器的代理

• 控制帧更新

  • paused 布尔值,渲染循环是否已暂停
  • pausedOnWillResignActive 布尔值,当前程序重新激活活动状态时视图控制器是否⾃动暂停渲染循环
  • resumeOnDidBecomeActive 布尔值,当前程序变为活动状态时视图控制是否自动恢复呈现循环

• 获取有关View 更新信息

  • frameDisplayed 视图控制器⾃创建以来发送的帧更新数
  • timeSinceFirstResume ⾃视图控制器第一次恢复发送更新事件以来经过的时间量
  • timeSinceLastResume 自上次视图控制器恢复发送更新事件以来更新的时间量
  • timeSinceLastUpdate ⾃上次视图控制器调用委托⽅法以及经过的时间量 glkViewControllerUpdate:
  • timeSinceLastDraw ⾃上次视图控制器调用视图display 方法以来经过的时间量.

4. GLKViewControllerDelegate 渲染循环回调⽅法

• 处理更新事件

  • -glkViewControllerUpdate: 在显示每个帧之前调⽤

• 暂停/恢复通知

  • -glkViewController:willPause: 在渲染循环暂停或恢复之前调⽤

5. GLKBaseEffect ⼀ species simple light / coloring system, based on OpenGL rendering shader

• Named Effect

  • label to Effect (effect) named

• Configuration model view conversion

  • Applied to the vertex data when the binding effect model view transform, projection transform, and texture

• Configuration lighting effects

  • Use lightingType in each segment is calculated illumination strategy, GLKLightingType
  • GLKLightingType
    • Each vertex represents GLKLightingTypePerVertex perform lighting calculations in a three-shaped ⻆ then interpolated three-shaped ⻆
    • GLKLightingTypePerPixel calculated input light represented in three ⻆ inserted shape, and each segment is calculated in the light YES

• Configuration of light

  • lightModelTwoSided Boolean value indicating the calculated illumination on both sides of the primitive
  • material calculated material properties rendering the primitive using light
  • lightModelAmbientColor ambient color, the effect of rendering the application of all elements.
  • a first frame light0 scene illumination properties
  • light1 second scene illumination properties
  • light2 third scene illumination properties

• Configuration texture

  • texture2d0 first texture attributes
  • texture2d1 second texture properties
  • textureOrder textures to rendered primitive sequence

• Configuration atomization

  • fog fog properties to apply it to the scene

• Of colors in the configuration information

  • colorMaterialEnable Boolean value that indicates whether the color of light and calculating the vertex attributes material interaction
  • useConstantColor Boolean value that indicates whether to use of colors in constant
  • ConstantColor constant color when using each vertex color data is not available

• Ready to draw results

  • -prepareToDraw ready to render effects

Reproduced in: https: //www.jianshu.com/p/5364db740e40