思維導圖
長截圖 2019-03-25 下午04.58.39.jpg
處理ArrayBuffer封裝
創(chuàng)建頂點緩存數(shù)組
// 此方法在當前的OpenGL ES上下文中創(chuàng)建一個頂點屬性數(shù)組緩沖區(qū)，用于調(diào)用此方法的線程.
- (id)initWithAttribStride:(GLsizeiptr)aStride
numberOfVertices:(GLsizei)count
bytes:(const GLvoid *)dataPtr
usage:(GLenum)usage;
{
NSParameterAssert(0 < aStride);
NSAssert((0 < count && NULL != dataPtr) ||
(0 == count && NULL == dataPtr),
@"data must not be NULL or count > 0");
if(nil != (self = [super init]))
{
stride = aStride;
bufferSizeBytes = stride * count;
// 第一步
glGenBuffers(1,
&name);
// 第二步
glBindBuffer(GL_ARRAY_BUFFER,
self.name);
// 第三步
glBufferData(
GL_ARRAY_BUFFER, // 初始化緩存區(qū)的內(nèi)容
bufferSizeBytes, // 要復制的字節(jié)數(shù)
dataPtr, // 要復制的字節(jié)地址
usage); //GPU內(nèi)存中的緩存
NSAssert(0 != name, @"Failed to generate name");
}
return self;
}
分配頂點數(shù)據(jù),準備繪制
// 當應用程序希望使用緩沖區(qū)呈現(xiàn)任何幾何圖形時枢贿，必須準備一個頂點屬性數(shù)組緩沖區(qū)。當你的應用程序準備一個緩沖區(qū)時，一些OpenGL ES狀態(tài)被改變橱赠，允許綁定緩沖區(qū)和配置指針。
- (void)prepareToDrawWithAttrib:(GLuint)index
numberOfCoordinates:(GLint)count
attribOffset:(GLsizeiptr)offset
shouldEnable:(BOOL)shouldEnable
{
NSParameterAssert((0 < count) && (count < 4));
NSParameterAssert(offset < self.stride);
NSAssert(0 != name, @"Invalid name");
glBindBuffer(GL_ARRAY_BUFFER,
self.name);
if(shouldEnable)
{
glEnableVertexAttribArray(index);
}
glVertexAttribPointer(
index,
count,
GL_FLOAT,
GL_FALSE,
self.stride,
NULL + offset);
#ifdef DEBUG
{
GLenum error = glGetError();
if(GL_NO_ERROR != error)
{
NSLog(@"GL Error: 0x%x", error);
}
}
#endif
}
繪制
// 提交由模式標識的繪圖命令箫津，并指示OpenGL ES從準備好的緩沖區(qū)中的頂點開始狭姨，從先前準備好的緩沖區(qū)中使用計數(shù)頂點。
+ (void)drawPreparedArraysWithMode:(GLenum)mode
startVertexIndex:(GLint)first
numberOfVertices:(GLsizei)count;
{
glDrawArrays(mode, first, count);
}
重新緩存頂點數(shù)組
// 此方法加載由接收器存儲的數(shù)據(jù)
- (void)reinitWithAttribStride:(GLsizeiptr)aStride
numberOfVertices:(GLsizei)count
bytes:(const GLvoid *)dataPtr;
{
NSParameterAssert(0 < aStride);
NSParameterAssert(0 < count);
NSParameterAssert(NULL != dataPtr);
NSAssert(0 != name, @"Invalid name");
self.stride = aStride;
self.bufferSizeBytes = aStride * count;
// 第二步
glBindBuffer(GL_ARRAY_BUFFER,
self.name);
// 第三步
glBufferData(
GL_ARRAY_BUFFER,
bufferSizeBytes,
dataPtr,
GL_DYNAMIC_DRAW);
}
ViewDidLoad
新建opengles上下文及GLKView配置
//1.新建OpenGL ES 上下文
self.mContext = [[EAGLContext alloc]initWithAPI:kEAGLRenderingAPIOpenGLES2];
//2.獲取GLKView
GLKView *view = (GLKView *)self.view;
view.context = self.mContext;
view.drawableColorFormat = GLKViewDrawableColorFormatRGBA8888;
view.drawableDepthFormat = GLKViewDrawableDepthFormat24;
[EAGLContext setCurrentContext:self.mContext];
配置baseEffect光照信息
//創(chuàng)建GLKBaseEffect 只能有3個光照苏遥、2個紋理
self.baseEffect = [[GLKBaseEffect alloc]init];
-(void)configureLight
{
//1.是否開啟light0光照
self.baseEffect.light0.enabled = GL_TRUE;
/*
union _GLKVector4
{
struct { float x, y, z, w; };
struct { float r, g, b, a; };
struct { float s, t, p, q; };
float v[4];
} __attribute__((aligned(16)));
typedef union _GLKVector4 GLKVector4;
union共用體
有3個結(jié)構(gòu)體饼拍，
比如表示頂點坐標的x,y,z,w
比如表示顏色的，RGBA;
表示紋理的stpq
*/
//2.設(shè)置漫射光顏色
self.baseEffect.light0.diffuseColor = GLKVector4Make(
1.0f,//Red
1.0f,//Green
1.0f,//Blue
1.0f);//Alpha
/*
The position of the light in world coordinates.
世界坐標中的光的位置田炭。
If the w component of the position is 0.0, the light is calculated using the directional light formula. The x, y, and z components of the vector specify the direction the light shines. The light is assumed to be infinitely far away; attenuation and spotlight properties are ignored.
如果位置的w分量為0师抄，則使用定向光公式計算光。向量的x教硫、y和z分量指定光的方向叨吮。光被認為是無限遠的，衰減和聚光燈屬性被忽略栋豫。
If the w component of the position is a non-zero value, the coordinates specify the position of the light in homogenous coordinates, and the light is either calculated as a point light or a spotlight, depending on the value of the spotCutoff property.
如果該位置的W組件是一個非零的值挤安，指定的坐標的光在齊次坐標的位置，和光是一個點光源和聚光燈計算丧鸯，根據(jù)不同的spotcutoff屬性的值
The default value is [0.0, 0.0, 1.0, 0.0].
默認值[0.0f,0.0f,1.0f,0.0f];
*/
self.baseEffect.light0.position = GLKVector4Make(
1.0f, //x
0.0f, //y
0.8f, //z
0.0f);//w
//光的環(huán)境部分
self.baseEffect.light0.ambientColor = GLKVector4Make(
0.2f,//Red
0.2f,//Green
0.2f,//Blue
1.0f);//Alpha
}
設(shè)置模型矩陣,投影矩陣
//獲取屏幕縱橫比
GLfloat aspectRatio = self.view.bounds.size.width / self.view.bounds.size.height;
//4.創(chuàng)建投影矩陣 -> 透視投影
self.baseEffect.transform.projectionMatrix = GLKMatrix4MakeOrtho(-1.0 * aspectRatio, 1.0 * aspectRatio, -1.0, 1.0, 1.0, 120.0f);
//5.設(shè)置模型矩陣 -5.0f表示往屏幕內(nèi)移動-5.0f距離
self.baseEffect.transform.modelviewMatrix = GLKMatrix4MakeTranslation(0.0f, 0.0f, -5.0f);
處理頂點數(shù)據(jù)
-(void)bufferData
{
//1蛤铜、GLKMatrixStackCreate()創(chuàng)建一個新的空矩陣
self.modelViewMatrixStack = GLKMatrixStackCreate(kCFAllocatorDefault);
//2、為將要緩存區(qū)數(shù)據(jù)開辟空間
//sphereVerts 在sphere.h文件中存在
/*
參數(shù)1：數(shù)據(jù)大小 3個GLFloat類型丛肢，x,y,z
參數(shù)2：有多少個數(shù)據(jù)围肥，count
參數(shù)3：數(shù)據(jù)大小
參數(shù)4：用途 GL_STATIC_DRAW，
*/
//頂點數(shù)據(jù)緩存蜂怎，頂點數(shù)據(jù)從sphere.h文件的sphereVerts數(shù)組中獲取頂點數(shù)據(jù)x,y,z
self.vertexPositionBuffer = [[AGLKVertexAttribArrayBuffer alloc]initWithAttribStride:(3 * sizeof(GLfloat)) numberOfVertices:sizeof(sphereVerts)/(3 * sizeof(GLfloat)) bytes:sphereVerts usage:GL_STATIC_DRAW];
//法線穆刻，光照坐標 sphereNormals數(shù)組 x,y,z
self.vertexNormalBuffer = [[AGLKVertexAttribArrayBuffer alloc]initWithAttribStride:(3 * sizeof(GLfloat)) numberOfVertices:sizeof(sphereNormals)/(3 * sizeof(GLfloat)) bytes:sphereNormals usage:GL_STATIC_DRAW];
//紋理坐標 sphereTexCoords數(shù)組 x,y
self.vertextTextureCoordBuffer = [[AGLKVertexAttribArrayBuffer alloc]initWithAttribStride:(2 * sizeof(GLfloat)) numberOfVertices:sizeof(sphereTexCoords)/ (2 * sizeof(GLfloat)) bytes:sphereTexCoords usage:GL_STATIC_DRAW];
//3.獲取地球紋理
CGImageRef earthImageRef = [UIImage imageNamed:@"Earth512x256.jpg"].CGImage;
//控制圖像加載方式的選項
NSDictionary *earthOptions = [NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithBool:YES],GLKTextureLoaderOriginBottomLeft, nil];
//將紋理圖片加載到紋理數(shù)據(jù)對象earchTextureInfo中
/*
參數(shù)1:加載的紋理圖片
參數(shù)2:控制圖像加載的方式的選項-字典
參數(shù)3:錯誤信息
*/
self.earchTextureInfo = [GLKTextureLoader textureWithCGImage:earthImageRef options:earthOptions error:NULL];
//4.獲取月亮紋理
CGImageRef moonImageRef = [UIImage imageNamed:@"Moon256x128"].CGImage;
NSDictionary *moonOptions = [NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithBool:YES],GLKTextureLoaderOriginBottomLeft, nil];
self.moomTextureInfo = [GLKTextureLoader textureWithCGImage:moonImageRef options:moonOptions error:NULL];
//矩陣堆
//用所提供的矩陣替換最頂層矩陣,將self.baseEffect.transform.modelviewMatrix,替換self.modelViewMatrixStack
GLKMatrixStackLoadMatrix4(self.modelViewMatrixStack, self.baseEffect.transform.modelviewMatrix);
//初始化在軌道上月球位置
self.moonRotationAngleDegress = -20.0f;
}
渲染場景
#pragma mark - drawRect
//渲染場景
-(void)glkView:(GLKView *)view drawInRect:(CGRect)rect
{
//設(shè)置清屏顏色
glClearColor(0.3f, 0.3f, 0.3f, 1.0f);
//清空顏色緩存區(qū)和深度緩存區(qū)
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
//地球旋轉(zhuǎn)角度
_earthRotationAngleDegress += 360.0f/60.0f;
//月球旋轉(zhuǎn)角度
_moonRotationAngleDegress += (360.0f/60.0f)/SceneDaysPerMoonOrbit;
//2、準備繪制
/*
其實就是把數(shù)據(jù)傳遞過去杠步，然后指定讀取方式
參數(shù)1：數(shù)據(jù)是做什么用的
參數(shù)2：數(shù)據(jù)讀取個數(shù)
參數(shù)3：數(shù)據(jù)讀取索引
參數(shù)4：是否調(diào)用glEnableVertexAttribArray
著色器能否讀取到數(shù)據(jù)氢伟，由是否啟用了對應的屬性決定榜轿，這就是glEnableVertexAttribArray的功能，允許頂點著色器讀取GPU（服務器端）數(shù)據(jù)朵锣。
默認情況下谬盐，出于性能考慮，所有頂點著色器的屬性（Attribute）變量都是關(guān)閉的诚些，意味著數(shù)據(jù)在著色器端是不可見的飞傀，哪怕數(shù)據(jù)已經(jīng)上傳到GPU，由glEnableVertexAttribArray啟用指定屬性诬烹，才可在頂點著色器中訪問逐頂點的屬性數(shù)據(jù)砸烦。glVertexAttribPointer或VBO只是建立CPU和GPU之間的邏輯連接，從而實現(xiàn)了CPU數(shù)據(jù)上傳至GPU绞吁。但是幢痘，數(shù)據(jù)在GPU端是否可見，即家破，著色器能否讀取到數(shù)據(jù)雪隧，由是否啟用了對應的屬性決定，這就是glEnableVertexAttribArray的功能员舵，允許頂點著色器讀取GPU（服務器端）數(shù)據(jù)。
那么藕畔，glEnableVertexAttribArray應該在glVertexAttribPointer之前還是之后調(diào)用马僻？答案是都可以，只要在繪圖調(diào)用（glDraw*系列函數(shù)）前調(diào)用即可注服。
*/
[self.vertexPositionBuffer prepareToDrawWithAttrib:GLKVertexAttribPosition numberOfCoordinates:3 attribOffset:0 shouldEnable:YES];
[self.vertexNormalBuffer prepareToDrawWithAttrib:GLKVertexAttribNormal numberOfCoordinates:3 attribOffset:0 shouldEnable:YES];
[self.vertextTextureCoordBuffer prepareToDrawWithAttrib:GLKVertexAttribTexCoord0 numberOfCoordinates:2 attribOffset:0 shouldEnable:YES];
//3.開始繪制
[self drawEarth];
[self drawMoon];
}
繪制地球
-(void)drawEarth
{
//獲取紋理的name韭邓、target
self.baseEffect.texture2d0.name = self.earchTextureInfo.name;
self.baseEffect.texture2d0.target = self.earchTextureInfo.target;
/*
current matrix:
1.000000 0.000000 0.000000 0.000000
0.000000 1.000000 0.000000 0.000000
0.000000 0.000000 1.000000 0.000000
0.000000 0.000000 -5.000000 1.000000
為什么？因為你在viewDidLoad中設(shè)置的
//5.設(shè)置模型矩形 -5.0f表示往屏幕內(nèi)移動-5.0f距離
self.baseEffect.transform.modelviewMatrix = GLKMatrix4MakeTranslation(0.0f, 0.0f, -5.0f);
*/
//將當前的modelViewMatrixStack 壓棧
GLKMatrixStackPush(self.modelViewMatrixStack);
//在指定的軸上旋轉(zhuǎn)最上面的矩陣溶弟。
GLKMatrixStackRotate(self.modelViewMatrixStack, GLKMathDegreesToRadians(SceneEarthAxialTiltDeg), 1.0f, 0.0f, 0.0f);
/*
current matrix:
1.000000 0.000000 0.000000 0.000000
0.000000 0.917060 0.398749 0.000000
0.000000 -0.398749 0.917060 0.000000
0.000000 0.000000 -5.000000 1.000000
為什么女淑？
將矩陣與圍繞X旋轉(zhuǎn)的旋轉(zhuǎn)矩陣相乘，即可得上述結(jié)果
*/
self.baseEffect.transform.modelviewMatrix = GLKMatrixStackGetMatrix4(self.modelViewMatrixStack);
//準備繪制
[self.baseEffect prepareToDraw];
//調(diào)用AGLKVertexAttribArrayBuffer辜御，繪制圖形
/*
參數(shù)1：繪制的方式鸭你，三角形
參數(shù)2：繪制數(shù)據(jù)讀取的索引
參數(shù)3：繪制數(shù)據(jù)的大小
*/
[AGLKVertexAttribArrayBuffer drawPreparedArraysWithMode:GL_TRIANGLES startVertexIndex:0 numberOfVertices:sphereNumVerts];
//繪制完畢，則出棧
/*
current matrix:
0.994522 0.041681 -0.095859 0.000000
0.000000 0.917060 0.398749 0.000000
0.104528 -0.396565 0.912036 0.000000
0.000000 0.000000 -5.000000 1.000000
*/
GLKMatrixStackPop(self.modelViewMatrixStack);
/*
current matrix:
1.000000 0.000000 0.000000 0.000000
0.000000 1.000000 0.000000 0.000000
0.000000 0.000000 1.000000 0.000000
0.000000 0.000000 -5.000000 1.000000
*/
self.baseEffect.transform.modelviewMatrix = GLKMatrixStackGetMatrix4(self.modelViewMatrixStack);
}
繪制月球
-(void)drawMoon
{
//獲取紋理的name擒权、target
self.baseEffect.texture2d0.name = self.moomTextureInfo.name;
self.baseEffect.texture2d0.target = self.moomTextureInfo.target;
//壓棧
GLKMatrixStackPush(self.modelViewMatrixStack);
//圍繞Y軸旋轉(zhuǎn)moonRotationAngleDegress角度
//自轉(zhuǎn)
GLKMatrixStackRotate(self.modelViewMatrixStack, GLKMathDegreesToRadians(self.moonRotationAngleDegress), 0.0f, 1.0f, 0.0f);
//平移 -月球距離地球的距離
GLKMatrixStackTranslate(self.modelViewMatrixStack, 0.0f, 0.0f, SceneMoonDistanceFromEarth);
//縮放袱巨，把月球縮放
GLKMatrixStackScale(self.modelViewMatrixStack, SceneMoonRadiusFractionOfEarth, SceneMoonRadiusFractionOfEarth, SceneMoonRadiusFractionOfEarth);
//旋轉(zhuǎn) 圍繞Y軸旋轉(zhuǎn)
GLKMatrixStackRotate(self.modelViewMatrixStack, GLKMathDegreesToRadians(self.moonRotationAngleDegress), 0.0f, 1.0f, 0.0f);
self.baseEffect.transform.modelviewMatrix = GLKMatrixStackGetMatrix4(self.modelViewMatrixStack);
[self.baseEffect prepareToDraw];
[AGLKVertexAttribArrayBuffer drawPreparedArraysWithMode:GL_TRIANGLES startVertexIndex:0 numberOfVertices:sphereNumVerts];
GLKMatrixStackPop(self.modelViewMatrixStack);
self.baseEffect.transform.modelviewMatrix = GLKMatrixStackGetMatrix4(self.modelViewMatrixStack);
}
切換投影方法
#pragma mark -Switch Click
//切換正投影效果或透視投影效果
- (IBAction)switchClick:(UISwitch *)sender {
GLfloat aspect = self.view.bounds.size.width / self.view.bounds.size.height;
if ([sender isOn]) {
//正投影
self.baseEffect.transform.projectionMatrix = GLKMatrix4MakeFrustum(-1.0 * aspect, 1.0 * aspect, -1.0, 1.0, 2.0, 120.0);
}else
{
//透視投影
self.baseEffect.transform.projectionMatrix = GLKMatrix4MakeOrtho(-1.0 * aspect, 1.0 * aspect, -1.0, 1.0, 2.0, 120.0);
}
}
效果圖
12.gif
13.gif
