在iOS开发中可以通过苹果提供的GLKBaseEffect来配置光照、纹理、缓冲区等信息，但其配置的信息有所限制并且无法跨平台使用，可以通过引入C/C++开发文件来实现跨平台开发，实现代码如下：
swift文件
import UIKit
import OpenGLES
import GLKit
class ViewController: GLKViewController, GLKViewControllerDelegate {
var context: EAGLContext!
var _esContext: ESContext!
override func viewDidLoad() {
super.viewDidLoad()
context = EAGLContext.init(api: .openGLES3)
guard let context = context else {
print("Failed to create es context")
return
}
let newView = self.view as! GLKView
newView.context = context
newView.drawableDepthFormat = .format24
self.delegate = self
setupGL()
}
deinit {
tearDownGL()
if EAGLContext.current() == self.context {
EAGLContext.setCurrent(nil)
}
}
}
extension ViewController {
func glkViewControllerUpdate(_ controller: GLKViewController) {
// 在swift中updata()方法不会调用，可以在此处调用或将逻辑移动到此处执行
update()
}
func setupGL() {
EAGLContext.setCurrent(self.context)
memset(&_esContext, 0, MemoryLayout.size(ofValue: _esContext))
_esContext.width = GLint(self.view.frame.width);
_esContext.height = GLint(self.view.frame.height);
esMain(&_esContext);
}
func update() {
if _esContext.updateFunc != nil {
_esContext.updateFunc(&_esContext, Float(self.timeSinceLastUpdate));
}
}
override func glkView(_ view: GLKView, drawIn rect: CGRect) {
_esContext.width = GLint(view.drawableWidth)
_esContext.height = GLint(view.drawableHeight)
if (_esContext.drawFunc != nil) {
_esContext.drawFunc(&_esContext)
}
}
func tearDownGL() {
EAGLContext.setCurrent(self.context)
if _esContext.shutdownFunc != nil {
_esContext.shutdownFunc(&_esContext)
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
if self.isViewLoaded && self.view.window == nil {
self.view = nil
tearDownGL()
if EAGLContext.current() == self.context {
EAGLContext.setCurrent(nil)
}
self.context = nil
}
}
}
C文件实现代码如下：
#include "Hello_Triangle.h"
//
typedef struct {
GLuint programObject;
} UserData;
GLuint LoadShader(GLenum type, const char *shaderSrc)
{
GLuint shader;
GLint compiled;
shader = glCreateShader(type);
if (shader == 0) {
return 0;
}
// 加载shader源文件
glShaderSource(shader, 1, &shaderSrc, NULL);
// 编译shader
glCompileShader(shader);
// 获取shader编译状态
glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
if (!compiled) {
// 获取编译中出错的问题
GLint infoLen = 0;
glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &infoLen);
if (infoLen > 1) {
char *infoLog = malloc(sizeof(char) * infoLen);
glGetShaderInfoLog(shader, infoLen, NULL, infoLog);
esLogMessage("Error compiling shader:\n %s\n", infoLog);
free(infoLog);
}
// 标记删除
glDeleteShader(shader);
return 0;
}
return shader;
}
int Init(ESContext * esContext)
{
UserData * userData = esContext->userData;
char vShaderStr[] =
"#version 300 es \n"
"layout(location = 0) in vec4 vPosition; \n"
"void main() \n"
"{ \n"
" gl_Position = vPosition; \n"
"} \n";
char fShaderStr[] =
"#version 300 es \n"
"precision mediump float; \n"
"out vec4 fragColor; \n"
"void main() \n"
"{ \n"
" fragColor = vec4 ( 1.0, 0.0, 0.0, 1.0 ); \n"
"} \n";
GLuint vertexShader;
GLuint fragmentShader;
GLuint programObject;
GLint linked;
// 加载顶点着色器和片源着色器
vertexShader = LoadShader(GL_VERTEX_SHADER, vShaderStr);
fragmentShader = LoadShader(GL_FRAGMENT_SHADER, fShaderStr);
// 创建链接器
programObject = glCreateProgram();
if (programObject == 0) {
return 0;
}
// 绑定shader
glAttachShader(programObject, vertexShader);
glAttachShader(programObject, fragmentShader);
// 链接链接器
glLinkProgram(programObject);
// 获取链接器状态
glGetProgramiv(programObject, GL_LINK_STATUS, &linked);
if (!linked) { // 如果链接器连接失败
// 获取日志长度
GLint infoLen = 0;
glGetProgramiv(programObject, GL_INFO_LOG_LENGTH, &infoLen);
// 获取输出日志
if (infoLen > 1) {
char *infoLog = malloc(sizeof(char) * infoLen);
glGetProgramInfoLog(programObject, infoLen, NULL, infoLog);
free(infoLog);
}
// 失败时删除程序，并返回失败
glDeleteProgram(programObject);
return FALSE;
}
// 标记删除，当所有链接断开后才会释放
glDeleteShader(vertexShader);
glDeleteShader(fragmentShader);
// 将链接器存储起来
userData->programObject = programObject;
glClearColor(1.0f, 1.0f, 1.0f, 0.0f);
return GL_TRUE;
}
// 绘制三角形
void Draw(ESContext * esContext)
{
UserData * userData = esContext->userData;
GLfloat vVertices[] = {
0.0f, 0.5f, 0.0f,
-0.5f, -0.5f, 0.0f,
0.5f, -0.5f, 0.0f
};
// 设置视口
glViewport(0, 0, esContext->width, esContext->height);
// 清除缓存区颜色
glClear(GL_COLOR_BUFFER_BIT);
// 设置连接器
glUseProgram(userData->programObject);
// 获取vPosition在链接器中的位置，也可以直接使用layout(location = 0) in vec4 vPosition;中location的值
GLint location = glGetAttribLocation(userData->programObject, "vPosition");
/**
glVertexAttribPointer(GLuint indx, GLint size, GLenum type, GLboolean normalized, GLsizei stride, const GLvoid *ptr)
*/
// 将vvertices数据绑定到顶点着色器
/**
glVertexAttribPointer(GLuint indx, GLint size, GLenum type, GLboolean normalized, GLsizei stride, const GLvoid *ptr)
indx: 指定要修改的顶点属性的索引值，即在着色器中指定的统一变量的编号
size: 每次读取数据的个数（如position是由3个（x,y,z）组成，而颜色是4个（r,g,b,a）,纹理则是2个.）
type: 数据类型，可用的符号常量有GL_BYTE, GL_UNSIGNED_BYTE, GL_SHORT,GL_UNSIGNED_SHORT, GL_FIXED, 和 GL_FLOAT，初始值为GL_FLOAT。
normalized: 指定当被访问时，固定点数据值是否应该被归一化（GL_TRUE）或者直接转换为固定点值（GL_FALSE）
stride:指定连续顶点属性之间的偏移量。如果为0，那么顶点属性会被理解为：它们是紧密排列在一起的。初始值为0
ptr:指定一个指针，指向数组中第一个顶点属性的第一个组件。初始值为0
*/
glVertexAttribPointer(location, 3, GL_FLOAT, GL_FALSE, 0, vVertices);
//数据在GPU端是否可见，即，着色器能否读取到数据，由是否启用了对应的属性决定，这就是glEnableVertexAttribArray的功能，允许顶点着色器读取GPU（服务器端）数据
glEnableVertexAttribArray(0);
/**
glDrawArrays(GLenum mode, GLint first, GLsizei count)
*/
glDrawArrays(GL_TRIANGLES, 0, 3);
}
void Shutdown(ESContext *esContext)
{
UserData * userData = esContext->userData;
glDeleteProgram(userData->programObject);
}
int esMain ( ESContext *esContext )
{
esContext->userData = malloc(sizeof(UserData));
esCreateWindow(esContext, "Hello Triangle", esContext->width, esContext->height, ES_WINDOW_RGB);
if (!Init(esContext)) {
return GL_FALSE;
}
// 注册释放和绘制方法
esRegisterShutdownFunc(esContext, Shutdown);
esRegisterDrawFunc(esContext, Draw);
return GL_TRUE;
}
网友评论