无分屏滤镜
一、GLSL自定义着色器
- Normal.vsh:顶点着色器
attribute vec4 Position;
attribute vec2 TextureCoords;
varying vec2 TextureCoordsVarying;
void main (void) {
gl_Position = Position;
TextureCoordsVarying = TextureCoords;
}
- Normal.fsh:片元着色器
precision highp float;
uniform sampler2D Texture;
varying vec2 TextureCoordsVarying;
void main (void) {
vec4 mask = texture2D(Texture, TextureCoordsVarying);
gl_FragColor = vec4(mask.rgb, 1.0);
}
二、ViewController
创建滤镜切换栏
- 定义全局需要使用的变量
typedef struct {
GLKVector3 positionCoord; // (X, Y, Z)
GLKVector2 textureCoord; // (U, V)
} SenceVertex;
@property (nonatomic, assign) SenceVertex *vertices;
// Context
@property (nonatomic, strong) EAGLContext *context;
// 用于刷新屏幕
@property (nonatomic, strong) CADisplayLink *displayLink;
// 开始的时间戳
@property (nonatomic, assign) NSTimeInterval startTimeInterval;
// 着色器程序
@property (nonatomic, assign) GLuint program;
// 顶点缓存
@property (nonatomic, assign) GLuint vertexBuffer;
// 纹理 ID
@property (nonatomic, assign) GLuint textureID;
- 创建滤镜切换栏:
- (void)setupFilterBar {
CGFloat filterBarWidth = [UIScreen mainScreen].bounds.size.width;
CGFloat filterBarHeight = 100;
CGFloat filterBarY = [UIScreen mainScreen].bounds.size.height - filterBarHeight;
FilterBar *filerBar = [[FilterBar alloc] initWithFrame:CGRectMake(0, filterBarY, filterBarWidth, filterBarHeight)];
filerBar.delegate = self;
[self.view addSubview:filerBar];
NSArray *dataSource = @[@"无"];
filerBar.itemList = dataSource;
}
- FilterBarDelegate实现
#pragma mark - FilterBarDelegate
- (void)filterBar:(FilterBar *)filterBar didScrollToIndex:(NSUInteger)index {
// 选择默认shader
if (index == 0) {
[self setupNormalShaderProgram];
}
// 渲染
[self render];
}
- 渲染
- (void)render {
// 清除画布
glClear(GL_COLOR_BUFFER_BIT);
glClearColor(1, 1, 1, 1);
// 使用program
glUseProgram(self.program);
// 绑定buffer
glBindBuffer(GL_ARRAY_BUFFER, self.vertexBuffer);
// 重绘
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
// 渲染到屏幕上
[self.context presentRenderbuffer:GL_RENDERBUFFER];
}
滤镜处理初始化
- 设置上下文,开辟顶点数组内存空间并初始化顶点坐标和纹理坐标;
// 初始化上下文并设置为当前上下文
self.context = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];
[EAGLContext setCurrentContext:self.context];
// 开辟顶点数组内存空间
self.vertices = malloc(sizeof(SenceVertex) * 4);
// 初始化顶点(0,1,2,3)的顶点坐标以及纹理坐标
self.vertices[0] = (SenceVertex){{-1, 1, 0}, {0, 1}};
self.vertices[1] = (SenceVertex){{-1, -1, 0}, {0, 0}};
self.vertices[2] = (SenceVertex){{1, 1, 0}, {1, 1}};
self.vertices[3] = (SenceVertex){{1, -1, 0}, {1, 0}};
- 创建图层并绑定渲染缓存区
// 创建图层(CAEAGLLayer)
CAEAGLLayer *layer = [[CAEAGLLayer alloc] init];
// 设置图层frame
layer.frame = CGRectMake(0, 100, self.view.frame.size.width, self.view.frame.size.width);
// 设置图层的scale
layer.contentsScale = [[UIScreen mainScreen] scale];
// 给View添加layer
[self.view.layer addSublayer:layer];
// 绑定渲染缓存区
[self bindRenderLayer:layer];
- 设置纹理图片,并创建视口,设置顶点缓存区
// 读取图片
UIImage *image = [UIImage imageWithContentsOfFile:imagePath];
// 将JPG图片转换成纹理图片
GLuint textureID = [self createTextureWithImage:image];
// 设置纹理ID
self.textureID = textureID; // 将纹理 ID 保存,方便后面切换滤镜的时候重用
// 设置视口
glViewport(0, 0, self.drawableWidth, self.drawableHeight);
// 设置顶点缓存区
GLuint vertexBuffer;
glGenBuffers(1, &vertexBuffer);
glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
GLsizeiptr bufferSizeBytes = sizeof(SenceVertex) * 4;
glBufferData(GL_ARRAY_BUFFER, bufferSizeBytes, self.vertices, GL_STATIC_DRAW);
// 设置默认着色器:开始选用默认的着色器
[self setupNormalShaderProgram];
// 将顶点缓存保存,退出时才释放
self.vertexBuffer = vertexBuffer;
// 获取渲染缓存区的宽
- (GLint)drawableWidth {
GLint backingWidth;
glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH, &backingWidth);
return backingWidth;
}
// 获取渲染缓存区的高
- (GLint)drawableHeight {
GLint backingHeight;
glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &backingHeight);
return backingHeight;
}
- 绑定渲染缓存区和帧缓存区
- (void)bindRenderLayer:(CALayer <EAGLDrawable> *)layer {
// 渲染缓存区,帧缓存区对象
GLuint renderBuffer;
GLuint frameBuffer;
// 获取帧渲染缓存区名称,绑定渲染缓存区以及将渲染缓存区与layer建立连接
glGenRenderbuffers(1, &renderBuffer);
glBindRenderbuffer(GL_RENDERBUFFER, renderBuffer);
[self.context renderbufferStorage:GL_RENDERBUFFER fromDrawable:layer];
// 获取帧缓存区名称,绑定帧缓存区以及将渲染缓存区附着到帧缓存区上
glGenFramebuffers(1, &frameBuffer);
glBindFramebuffer(GL_FRAMEBUFFER, frameBuffer);
glFramebufferRenderbuffer(GL_FRAMEBUFFER,
GL_COLOR_ATTACHMENT0,
GL_RENDERBUFFER,
renderBuffer);
}
- 从图片中加载纹理
// 从图片中加载纹理
- (GLuint)createTextureWithImage:(UIImage *)image {
// 将 UIImage 转换为 CGImageRef
CGImageRef cgImageRef = [image CGImage];
// 判断图片是否获取成功
if (!cgImageRef) {
NSLog(@"Failed to load image");
exit(1);
}
// 读取图片的大小,宽和高
GLuint width = (GLuint)CGImageGetWidth(cgImageRef);
GLuint height = (GLuint)CGImageGetHeight(cgImageRef);
// 获取图片的rect
CGRect rect = CGRectMake(0, 0, width, height);
// 获取图片的颜色空间
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
// 获取图片字节数 宽*高*4(RGBA)
void *imageData = malloc(width * height * 4);
/* 创建上下文
* 参数1:data,指向要渲染的绘制图像的内存地址
* 参数2:width,bitmap的宽度,单位为像素
* 参数3:height,bitmap的高度,单位为像素
* 参数4:bitPerComponent,内存中像素的每个组件的位数,比如32位RGBA,就设置为8
* 参数5:bytesPerRow,bitmap的没一行的内存所占的比特数
* 参数6:colorSpace,bitmap上使用的颜色空间 kCGImageAlphaPremultipliedLast:RGBA
*/
CGContextRef context = CGBitmapContextCreate(imageData, width, height, 8, width * 4, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
// 将图片翻转过来(图片默认是倒置的)
CGContextTranslateCTM(context, 0, height);
CGContextScaleCTM(context, 1.0f, -1.0f);
CGColorSpaceRelease(colorSpace);
CGContextClearRect(context, rect);
// 对图片进行重新绘制,得到一张新的解压缩后的位图
CGContextDrawImage(context, rect, cgImageRef);
// 设置图片纹理属性
// 获取纹理ID
GLuint textureID;
glGenTextures(1, &textureID);
glBindTexture(GL_TEXTURE_2D, textureID);
/* 载入纹理2D数据
* 参数1:纹理模式,GL_TEXTURE_1D、GL_TEXTURE_2D、GL_TEXTURE_3D
* 参数2:加载的层次,一般设置为0
* 参数3:纹理的颜色值GL_RGBA
* 参数4:宽
* 参数5:高
* 参数6:border,边界宽度
* 参数7:format
* 参数8:type
* 参数9:纹理数据
*/
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageData);
// 设置纹理属性
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
/* 绑定纹理
* 参数1:纹理维度
* 参数2:纹理ID,因为只有一个纹理,给0就可以了。
*/
glBindTexture(GL_TEXTURE_2D, 0);
// 释放context,imageData
CGContextRelease(context);
free(imageData);
// 返回纹理ID
return textureID;
}
- 设置滤镜动画
- (void)startFilerAnimation {
// 判断 displayLink 是否为空
// CADisplayLink 定时器
if (self.displayLink) {
[self.displayLink invalidate];
self.displayLink = nil;
}
// 设置 displayLink 的方法
self.startTimeInterval = 0;
self.displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(timeAction)];
// 将 displayLink 添加到 runloop 运行循环
[self.displayLink addToRunLoop:[NSRunLoop mainRunLoop]
forMode:NSRunLoopCommonModes];
}
- (void)timeAction {
// DisplayLink 的当前时间戳
if (self.startTimeInterval == 0) {
self.startTimeInterval = self.displayLink.timestamp;
}
// 使用program
glUseProgram(self.program);
// 绑定buffer
glBindBuffer(GL_ARRAY_BUFFER, self.vertexBuffer);
// 传入时间
CGFloat currentTime = self.displayLink.timestamp - self.startTimeInterval;
GLuint time = glGetUniformLocation(self.program, "Time");
glUniform1f(time, currentTime);
// 清除画布
glClear(GL_COLOR_BUFFER_BIT);
glClearColor(1, 1, 1, 1);
// 重绘
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
// 渲染到屏幕上
[self.context presentRenderbuffer:GL_RENDERBUFFER];
}
着色器设定
- 着色器初始化
// 初始化着色器程序
- (void)setupShaderProgramWithName:(NSString *)name {
// 获取着色器program
GLuint program = [self programWithShaderName:name];
// use Program
glUseProgram(program);
// 获取Position,Texture,TextureCoords 的索引位置
GLuint positionSlot = glGetAttribLocation(program, "Position");
GLuint textureSlot = glGetUniformLocation(program, "Texture");
GLuint textureCoordsSlot = glGetAttribLocation(program, "TextureCoords");
// 激活纹理,绑定纹理ID
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, self.textureID);
// 纹理sample
glUniform1i(textureSlot, 0);
// 打开positionSlot 属性并且传递数据到positionSlot中(顶点坐标)
glEnableVertexAttribArray(positionSlot);
glVertexAttribPointer(positionSlot, 3, GL_FLOAT, GL_FALSE, sizeof(SenceVertex), NULL + offsetof(SenceVertex, positionCoord));
// 打开textureCoordsSlot 属性并传递数据到textureCoordsSlot(纹理坐标)
glEnableVertexAttribArray(textureCoordsSlot);
glVertexAttribPointer(textureCoordsSlot, 2, GL_FLOAT, GL_FALSE, sizeof(SenceVertex), NULL + offsetof(SenceVertex, textureCoord));
// 保存program,界面销毁则释放
self.program = program;
}
- 链接 Program
// link Program
- (GLuint)programWithShaderName:(NSString *)shaderName {
// 编译顶点着色器/片元着色器
GLuint vertexShader = [self compileShaderWithName:shaderName type:GL_VERTEX_SHADER];
GLuint fragmentShader = [self compileShaderWithName:shaderName type:GL_FRAGMENT_SHADER];
// 将顶点/片元附着到program
GLuint program = glCreateProgram();
glAttachShader(program, vertexShader);
glAttachShader(program, fragmentShader);
// linkProgram
glLinkProgram(program);
// 检查是否link成功
GLint linkSuccess;
glGetProgramiv(program, GL_LINK_STATUS, &linkSuccess);
if (linkSuccess == GL_FALSE) {
GLchar messages[256];
glGetProgramInfoLog(program, sizeof(messages), 0, &messages[0]);
NSString *messageString = [NSString stringWithUTF8String:messages];
NSAssert(NO, @"program链接失败:%@", messageString);
exit(1);
}
// 返回program
return program;
}
- 编译shader
- (GLuint)compileShaderWithName:(NSString *)name type:(GLenum)shaderType {
// 获取shader 路径
NSString *shaderPath = [[NSBundle mainBundle] pathForResource:name ofType:shaderType == GL_VERTEX_SHADER ? @"vsh" : @"fsh"];
NSError *error;
NSString *shaderString = [NSString stringWithContentsOfFile:shaderPath encoding:NSUTF8StringEncoding error:&error];
if (!shaderString) {
NSAssert(NO, @"读取shader失败");
exit(1);
}
// 创建shader->根据shaderType
GLuint shader = glCreateShader(shaderType);
// 获取shader source
const char *shaderStringUTF8 = [shaderString UTF8String];
int shaderStringLength = (int)[shaderString length];
glShaderSource(shader, 1, &shaderStringUTF8, &shaderStringLength);
// 编译shader
glCompileShader(shader);
// 查看编译是否成功
GLint compileSuccess;
glGetShaderiv(shader, GL_COMPILE_STATUS, &compileSuccess);
if (compileSuccess == GL_FALSE) {
GLchar messages[256];
glGetShaderInfoLog(shader, sizeof(messages), 0, &messages[0]);
NSString *messageString = [NSString stringWithUTF8String:messages];
NSAssert(NO, @"shader编译失败:%@", messageString);
exit(1);
}
// 返回shader
return shader;
}
调用GLSL代码执行滤镜效果
- (void)setupNormalShaderProgram {
// 设置着色器程序
[self setupShaderProgramWithName:@"Normal"];
}
效果展示
二分屏滤镜
一、实现原理
当实现二分屏滤镜时,图片纹理坐标的x值是没有任何变化的,主要是y值变化:
- 当 y 在[0, 0.5]范围时,屏幕的(0,0)坐标需要对应图片的(0,0.25),所以y = y+0.25
- 当 y 在[0.5, 1]范围时,屏幕的(0,0.5)坐标需要对应图片的(0,0.25),所以y = y-0.25
二、实现流程
- 新建TwoSplitScreen.vsh和TwoSplitScreen.fsh,着色器的代码与上面的“无分屏滤镜”一样,只需要修改TwoSplitScreen.fsh的main函数实现:
void main(){
vec2 uv = TextureCoordsVarying.xy;
float y;
if (uv.y >= 0.0 && uv.y <= 0.5) {
y = uv.y + 0.25;
}else{
y = uv.y - 0.25;
}
gl_FragColor = texture2D(Texture, vec2(uv.x, y));
}
- 在FilterBarDelegate实现调用“二分屏”的GLSL代码
- (void)filterBar:(FilterBar *)filterBar didScrollToIndex:(NSUInteger)index {
// 选择默认shader
if (index == 0) {
[self setupNormalShaderProgram];
} else if (index == 1) {
[self setupSplitScreen_2ShaderProgram];
}
// 渲染
[self render];
}
// 二分屏
- (void)setupSplitScreen_2ShaderProgram {
[self setupShaderProgramWithName:@"TwoSplitScreen"];
}
三、效果展示
三分屏滤镜
一、实现原理
当实现三分屏滤镜时,即为显示的图片三等分,图片纹理坐标的x值是没有任何变化的,主要是y值变化:
- 当 y 在[0, 1/3]范围时,屏幕的(0,0)坐标需要对应图片的(0,1/3),所以y = y+1/3
- 当 y 在[1/3, 2/3]范围时,屏幕的(0,1/3)坐标需要对应图片的(0,1/3),所以y 不变
- 当 y 在[2/3, 1]范围时,屏幕的(0,2/3)坐标需要对应图片的(0,1/3),所以y = y-1/3
二、实现流程
- 新建ThreeSplitScreen.vsh和ThreeSplitScreen.fsh,着色器的代码与上面的“无分屏滤镜”一样,只需要修改ThreeSplitScreen.fsh的main函数实现:
precision highp float;
uniform sampler2D Texture;
varying vec2 TextureCoordsVarying;
void main(){
vec2 uv = TextureCoordsVarying.xy;
if (uv.y < 1.0/3.0) {
uv.y = uv.y + 1.0/3.0;
} else if (uv.y > 2.0/3.0) {
uv.y = uv.y - 1.0/3.0;
}
gl_FragColor = texture2D(Texture, uv);
}
- 在FilterBarDelegate实现调用“三分屏”的GLSL代码
- (void)filterBar:(FilterBar *)filterBar didScrollToIndex:(NSUInteger)index {
// 选择默认shader
if (index == 0) {
[self setupNormalShaderProgram];
} else if (index == 1) {
[self setupSplitScreen_2ShaderProgram];
} else if (index == 2) {
[self setupSplitScreen_3ShaderProgram];
}
// 渲染
[self render];
}
// 三分屏
- (void)setupSplitScreen_3ShaderProgram {
[self setupShaderProgramWithName:@"ThreeSplitScreen"];
}
三、效果展示
四分屏滤镜
一、实现原理
- 四分屏的显示是屏幕四等分,分别显示缩小的纹理图片纹理图片,与屏幕的映射既可以是一致的坐标,也可以映射到缩小的坐标
- 当实现四分屏时,纹理坐标x、y均需要变化,且屏幕坐标需要与纹理坐标一一映射,例如(x,y)取值(0.5,0.5)需要映射到纹理坐标(1,1)时,x、y均需要乘以2,即0.5 * 2 = 1,变化规则如下:
当 x 在[0, 0.5]范围时,x = x*2
当 x在[0.5, 1]范围时,x = (x-0.5)2
当 y 在[0, 0.5]范围时,y = y2
当 y 在[0.5, 1]范围时,y = (y-0.5)*2
二、实现流程
- 新建FourSplitScreen.vsh和FourSplitScreen.fsh,着色器的代码与上面的“无分屏滤镜”一样,只需要修改FourSplitScreen.fsh的main函数实现:
precision highp float;
uniform sampler2D Texture;
varying vec2 TextureCoordsVarying;
void main(){
vec2 uv = TextureCoordsVarying.xy;
if (uv.x <= 0.5) {
uv.x = uv.x * 2.0;
} else {
uv.x = (uv.x - 0.5) * 2.0;
}
if (uv.y <= 0.5) {
uv.y = uv.y * 2.0;
} else {
uv.y = (uv.y - 0.5) * 2.0;
}
gl_FragColor = texture2D(Texture, uv);
}
- 在FilterBarDelegate实现调用“四分屏”的GLSL代码
- (void)filterBar:(FilterBar *)filterBar didScrollToIndex:(NSUInteger)index {
// 选择默认shader
if (index == 0) {
[self setupNormalShaderProgram];
} else if (index == 1) {
[self setupSplitScreen_2ShaderProgram];
} else if (index == 2) {
[self setupSplitScreen_3ShaderProgram];
} else if (index == 3) {
[self setupSplitScreen_4ShaderProgram];
}
// 渲染
[self render];
}
// 四分屏
- (void)setupSplitScreen_4ShaderProgram {
[self setupShaderProgramWithName:@"FourSplitScreen"];
}
三、效果展示
六分屏滤镜与九分屏滤镜
与上述的“二分屏”“三分屏”“四分屏”的实现逻辑,只是片元着色器的实现逻辑不一样
-
当实现六分屏时,纹理坐标x、y均需要变化,其变化规则如下:
当 x 在[0, 1/3]范围时,x = x+1/3
当 x 在[1/3, 2/3]范围时,x 不变
当 x 在[2/3, 1]范围时,x = x-1/3
当 y 在[0, 0.5]范围时,y = y+0.25
当 y 在[0.5, 1]范围时,y = y-0.24 -
当实现九分屏时,纹理坐标x、y均需要变化,其变化规则如下:
当 x 在[0, 1/3]范围时,x = x*3
当 x 在[1/3, 2/3]范围时,x = (x-1/3)*3
当 x 在[2/3, 1]范围时,x = (x-2/3)3
当 y 在[0, 1/3]范围时,y= y3
当 y 在[1/3, 2/3]范围时,y = (y-1/3)*3
当 y在[2/3, 1]范围时,y = (y-2/3)*3
片元着色器的y修改如下:
- 六分屏
void main() {
vec2 uv = TextureCoordsVarying.xy;
if (uv.x <= 1.0/3.0) {
uv.x = uv.x + 1.0/3.0;
} else if (uv.x >= 2.0/3.0){
uv.x = uv.x - 1.0/3.0;
}
if (uv.y <= 0.5) {
uv.y = uv.y + 0.25;
} else {
uv.y = uv.y - 0.25;
}
gl_FragColor = texture2D(Texture, uv);
}
- 九分屏
void main(){
vec2 uv = TextureCoordsVarying.xy;
if (uv.x <= 1.0/3.0) {
uv.x = uv.x * 3.0;
} else if (uv.x >= 2.0/3.0) {
uv.x = (uv.x - 2.0/3.0) * 3.0;
} else {
uv.x = (uv.x - 1.0/3.0)*3.0;
}
if (uv.y <= 1.0/3.0) {
uv.y = uv.y * 3.0;
} else if (uv.y >= 2.0/3.0) {
uv.y = (uv.y - 2.0/3.0) * 3.0;
} else {
uv.y = (uv.y - 1.0/3.0)*3.0;
}
gl_FragColor = texture2D(Texture, uv);
}