QQ20200804-232115.gif
绘图流程
现在让我们一起探索，如何用自定义着色器索引绘制
注意：本案例使用了第三方的工具
在开始之前，需要在UIView导入需要的文件使用
#import "CCView.h"
#import "GLESMath.h"
#import "GLESUtils.h"
#import <OpenGLES/ES2/gl.h>
顶点着色器
attribute vec4 position;
attribute vec4 positionColor;
attribute vec2 textCoor;
uniform mat4 projectionMatrix;
uniform mat4 modelViewMatrix;
varying lowp vec4 varyColor;
varying lowp vec2 vTextCoor;
void main()
{
vTextCoor = textCoor;
varyColor = positionColor;
vec4 vPos;
vPos = projectionMatrix * modelViewMatrix * position;
gl_Position = vPos;
}
片元着色器
precision highp float;
varying lowp vec4 varyColor;
varying lowp vec2 vTextCoor;
uniform sampler2D colorMap;
void main(){
//(1)
//gl_FragColor = varyColor;
//(2).
//gl_FragColor = texture2D(colorMap,vTextCoor);
//(3).color&texture
vec4 weakMask = texture2D(colorMap,vTextCoor);
vec4 mask = varyColor;
float alpha = 0.3;
vec4 tempColor = mask * (1.0 - alpha) + weakMask * alpha;
gl_FragColor = tempColor;
}
绘制图层
//1.设置图层
-(void)setupLayer
{
self.myEagLayer = (CAEAGLLayer *)self.layer;
[self setContentScaleFactor:[[UIScreen mainScreen]scale]];
self.myEagLayer.opaque = YES;
self.myEagLayer.drawableProperties = [NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithBool:NO], kEAGLDrawablePropertyRetainedBacking,kEAGLColorFormatRGBA8, kEAGLDrawablePropertyColorFormat, nil];
}
+ (Class)layerClass {
return [CAEAGLLayer class];
}
设置上下文
-(void)setupContext
{
EAGLRenderingAPI api = kEAGLRenderingAPIOpenGLES2;
EAGLContext *context = [[EAGLContext alloc]initWithAPI:api];
if (!context) {
NSLog(@"Create Context Failed");
return;
}
if (![EAGLContext setCurrentContext:context]) {
NSLog(@"Set Current Context Failed");
return;
}
self.myContext = context;
}
清空缓存区
-(void)deletBuffer
{
glDeleteBuffers(1, &_myColorRenderBuffer);
_myColorRenderBuffer = 0;
glDeleteBuffers(1, &_myColorFrameBuffer);
_myColorFrameBuffer = 0;
}
设置renderBuffer
-(void)setupRenderBuffer
{
//1.定义一个缓存区
GLuint buffer;
//2.申请一个缓存区标志
glGenRenderbuffers(1, &buffer);
//3.
self.myColorRenderBuffer = buffer;
//4.将标识符绑定到GL_RENDERBUFFER
glBindRenderbuffer(GL_RENDERBUFFER, self.myColorRenderBuffer);
[self.myContext renderbufferStorage:GL_RENDERBUFFER fromDrawable:self.myEagLayer];
}
设置frameBuffer
-(void)setupFrameBuffer
{
//1.定义一个缓存区
GLuint buffer;
//2.申请一个缓存区标志
glGenFramebuffers(1, &buffer);
//3.
self.myColorFrameBuffer = buffer;
//4.设置当前的framebuffer
glBindFramebuffer(GL_FRAMEBUFFER, self.myColorFrameBuffer);
//5.将_myColorRenderBuffer 装配到GL_COLOR_ATTACHMENT0 附着点上
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, self.myColorRenderBuffer);
}
绘制
-(void)render
{
//重头戏
//1.
glClearColor(0, 0, 0, 1);
glClear(GL_COLOR_BUFFER_BIT);
//2.
CGFloat scale = [[UIScreen mainScreen]scale];
glViewport(self.frame.origin.x * scale, self.frame.origin.y * scale, self.frame.size.width * scale, self.frame.size.height * scale);
//3. 顶点着色器/片元着色器
NSString *vertFile = [[NSBundle mainBundle]pathForResource:@"shaderv" ofType:@"glsl"];
NSString *fragFile = [[NSBundle mainBundle]pathForResource:@"shaderf" ofType:@"glsl"];
//4.
if(self.myProgram){
glDeleteProgram(self.myProgram);
self.myProgram = 0;
}
//5.
self.myProgram = [self loadShader:vertFile frag:fragFile];
//6.
glLinkProgram(self.myProgram);
GLint linkSuccess;
//7.获取链接状态
glGetProgramiv(self.myProgram, GL_LINK_STATUS, &linkSuccess);
if (linkSuccess == GL_FALSE) {
GLchar messages[256];
glGetProgramInfoLog(self.myProgram, sizeof(messages), 0, &messages[0]);
NSString *messageString = [NSString stringWithUTF8String:messages];
NSLog(@"error%@", messageString);
return ;
}else {
glUseProgram(self.myProgram);
}
//8. 顶点数组.索引数组;
//(1)顶点数组 前3顶点值（x,y,z），后3位颜色值(RGB)
// GLfloat attrArr[] =
// {
// -0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 1.0f, //左上0
// 0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 1.0f, //右上1
// -0.5f, -0.5f, 0.0f, 1.0f, 1.0f, 1.0f, //左下2
//
// 0.5f, -0.5f, 0.0f, 1.0f, 1.0f, 1.0f, //右下3
// 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, //顶点4
// };
GLfloat attrArr[] =
{
-0.5f, 0.5f, 0.0f, 0.0f, 0.0f, 0.5f, 0.0f, 1.0f,//左上
0.5f, 0.5f, 0.0f, 0.0f, 0.5f, 0.0f, 1.0f, 1.0f,//右上
-0.5f, -0.5f, 0.0f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f,//左下
0.5f, -0.5f, 0.0f, 0.0f, 0.0f, 0.5f, 1.0f, 0.0f,//右下
0.0f, 0.0f, 1.0f, 1.0f, 1.0f, 1.0f, 0.5f, 0.5f,//顶点
};
//(2)索引数组
GLuint indices[] =
{
0, 3, 2,
0, 1, 3,
0, 2, 4,
0, 4, 1,
2, 3, 4,
1, 4, 3,
};
if(self.myVertices == 0){
glGenBuffers(1, &_myVertices);
}
glBindBuffer(GL_ARRAY_BUFFER, _myVertices);
glBufferData(GL_ARRAY_BUFFER, sizeof(attrArr), attrArr, GL_DYNAMIC_DRAW);
GLuint position = glGetAttribLocation(self.myProgram, "position");
glEnableVertexAttribArray(position);
glVertexAttribPointer(position, 3, GL_FLOAT, GL_FALSE, sizeof(GLfloat) * 8, NULL);
GLuint positionColor = glGetAttribLocation(self.myProgram, "positionColor");
glEnableVertexAttribArray(positionColor);
glVertexAttribPointer(positionColor, 3, GL_FLOAT, GL_FALSE, sizeof(GLfloat) * 8, (GLfloat *)NULL + 3);
GLuint textCoor = glGetAttribLocation(self.myProgram, "textCoor");
glEnableVertexAttribArray(textCoor);
glVertexAttribPointer(textCoor, 2, GL_FLOAT, GL_FALSE, sizeof(GLfloat) * 8, (GLfloat *)NULL + 6);
//加载纹理;-> 纹理解压
[self setupTexture:@"kunkun.jpg"];
glUniform1i(glGetUniformLocation(self.myProgram, "colorMap"), 0);
//mvp
GLuint projectionMatrixSlot = glGetUniformLocation(self.myProgram, "projectionMatrix");
GLuint modelViewMatrixSlot = glGetUniformLocation(self.myProgram, "modelViewMatrix");
float width = self.frame.size.width;
float height = self.frame.size.height;
//4*4 投影矩阵
KSMatrix4 _projectionMatrix;
ksMatrixLoadIdentity(&_projectionMatrix);
float aspect = width/height;
ksPerspective(&_projectionMatrix, 30.0f, aspect, 5.0f, 20.0f);
glUniformMatrix4fv(projectionMatrixSlot, 1, GL_FALSE, (GLfloat *)&_projectionMatrix.m[0][0]);
//4*4模型视图矩阵
KSMatrix4 _modelViewMatrix;
ksMatrixLoadIdentity(&_modelViewMatrix);
ksTranslate(&_modelViewMatrix, 0, 0, -10.0f);
KSMatrix4 _rotationMatrix;
ksMatrixLoadIdentity(&_rotationMatrix);
//XYZ
ksRotate(&_rotationMatrix, xDegree, 1.0, 0, 0);
ksRotate(&_rotationMatrix, yDegree, 0, 1, 0);
ksRotate(&_rotationMatrix, zDegree, 0, 0, 1);
//矩阵相乘
ksMatrixMultiply(&_modelViewMatrix, &_rotationMatrix, &_modelViewMatrix);
glUniformMatrix4fv(modelViewMatrixSlot, 1, GL_FALSE, (GLfloat *)&_modelViewMatrix.m[0][0]);
glEnable(GL_CULL_FACE);
//15.使用索引绘图
/*
void glDrawElements(GLenum mode,GLsizei count,GLenum type,const GLvoid * indices);
参数列表：
mode:要呈现的画图的模型
GL_POINTS
GL_LINES
GL_LINE_LOOP
GL_LINE_STRIP
GL_TRIANGLES
GL_TRIANGLE_STRIP
GL_TRIANGLE_FAN
count:绘图个数
type:类型
GL_BYTE
GL_UNSIGNED_BYTE
GL_SHORT
GL_UNSIGNED_SHORT
GL_INT
GL_UNSIGNED_INT
indices：绘制索引数组
*/
glDrawElements(GL_TRIANGLES, sizeof(indices)/sizeof(indices[0]), GL_UNSIGNED_INT, indices);
//
[self.myContext presentRenderbuffer:GL_RENDERBUFFER];
}
图片中加载纹理
- (GLuint)setupTexture:(NSString *)fileName {
//1、将 UIImage 转换为 CGImageRef
CGImageRef spriteImage = [UIImage imageNamed:fileName].CGImage;
//判断图片是否获取成功
if (!spriteImage) {
NSLog(@"Failed to load image %@", fileName);
exit(1);
}
//2、读取图片的大小，宽和高
size_t width = CGImageGetWidth(spriteImage);
size_t height = CGImageGetHeight(spriteImage);
//3.获取图片字节数 宽*高*4（RGBA）
GLubyte * spriteData = (GLubyte *) calloc(width * height * 4, sizeof(GLubyte));
//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 spriteContext = CGBitmapContextCreate(spriteData, width, height, 8, width*4,CGImageGetColorSpace(spriteImage), kCGImageAlphaPremultipliedLast);
//5、在CGContextRef上--> 将图片绘制出来
/*
CGContextDrawImage 使用的是Core Graphics框架，坐标系与UIKit 不一样。UIKit框架的原点在屏幕的左上角，Core Graphics框架的原点在屏幕的左下角。
CGContextDrawImage
参数1：绘图上下文
参数2：rect坐标
参数3：绘制的图片
*/
CGRect rect = CGRectMake(0, 0, width, height);
//6.使用默认方式绘制
CGContextDrawImage(spriteContext, rect, spriteImage);
//7、画图完毕就释放上下文
CGContextRelease(spriteContext);
//8、绑定纹理到默认的纹理ID（
glBindTexture(GL_TEXTURE_2D, 0);
//9.设置纹理属性
/*
参数1：纹理维度
参数2：线性过滤、为s,t坐标设置模式
参数3：wrapMode,环绕模式
*/
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
float fw = width, fh = height;
//10.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, fw, fh, 0, GL_RGBA, GL_UNSIGNED_BYTE, spriteData);
//11.释放spriteData
free(spriteData);
return 0;
}
上面就是就是我们绘制的全部流程
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