运行环境：
mac 10.12.2
xcode Version 8.2.1
cocos2dx-x-3.13.1
代码：
新建cocos2dx项目，具体操作官网有教程。新建好后，
新建Test.cpp，代码如下：
//
// Test.cpp
// Texture
//
// Created by zhufu on 2017/3/28.
//
//
#include "Test.h"
Test* Test::create()
{
Test* test = new(std::nothrow) Test();
if(test && test->init())
{
test->autorelease();
return test;
}
else
{
delete test;
test = nullptr;
return nullptr;
}
}
bool Test::init()
{
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
initCommand();
loadShader();
loadTexture();
loadRectangle();
return true;
}
void Test::flipVertical(int width, int height, unsigned char* arr)
{
int index = 0, f_index, cycle=height/2;
char buf;
for (int i = 0; i < cycle; i++)
{
for (int j = 0; j < width*Test::Format_RGBA; j++)
{
//当前像素
index = i*width*Test::Format_RGBA + j;
//需要交换的像素
f_index = (height - 1 - i)*width*Test::Format_RGBA + j;
//缓存当前像素
buf = arr[index];
//交换像素
arr[index] = arr[f_index];
//交换回像素
arr[f_index] = buf;
}
}
}
void Test::loadShader()
{
_glProgram = new GLProgram();
_glProgram->initWithFilenames("shader/myVertexShader.vsh", "shader/myFragmentShader.fsh");
_glProgram->link();
}
void Test::loadTexture()
{
Image *image = new Image;
std::string imagePath = FileUtils::getInstance()->fullPathForFilename("HelloWorld.png");
image->initWithImageFile(imagePath);
unsigned char *imageData = image->getData();
int width = image->getWidth();
int height = image->getHeight();
flipVertical(width, height, imageData);
CCLOG("width %d", width);
//别忘了释放image内存
// CC_SAFE_DELETE(image);
glGenTextures(1, &TEXTUREID);
glBindTexture(GL_TEXTURE_2D, TEXTUREID);
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);
glTexImage2D(GL_TEXTURE_2D,
0,
GL_RGBA,
width,
height,
0,
GL_RGBA,
GL_UNSIGNED_BYTE,
imageData);
glBindTexture(GL_TEXTURE_2D, 0);
}
void Test::loadRectangle()
{
glGenVertexArrays(1, &_vao);
glBindVertexArray(_vao);
//make and bind VBO;
GLuint vbo = 0;
glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
//put the rectangle vertices(XYZ) and texture coordinates (UV) into the vbo
GLfloat textureData[] = {
// X Y Z U V
-1.0f, 1.0f, 0.0f, 0.0f, 1.0f,
1.0f, 1.0f, 0.0f, 1.0f, 1.0f,
-1.0f,-1.0f, 0.0f, 0.0f, 0.0f,
1.0f,-1.0f , 0.0f, 1.0f, 0.0f,
};
glBufferData(GL_ARRAY_BUFFER, sizeof(textureData), textureData, GL_STATIC_DRAW);
//connect the xyz to the "vert" arrribute of the vertex shader
glEnableVertexAttribArray(_glProgram->getAttribLocation("vert"));
glVertexAttribPointer(_glProgram->getAttribLocation("vert"), 3, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), nullptr);
glEnableVertexAttribArray(_glProgram->getAttribLocation("vertTexCoord"));
glVertexAttribPointer(_glProgram->getAttribLocation("vertTexCoord"), 2, GL_FLOAT, GL_TRUE, 5 * sizeof(GLfloat), (const GLvoid*)(3*sizeof(GLfloat)));
}
void Test::initCommand()
{
_command.init(getLocalZOrder());
_command.func = CC_CALLBACK_0(Test::onDraw, this);
}
void Test::draw(Renderer *renderer, const Mat4 &transform, uint32_t platform)
{
Director::getInstance()->getRenderer()->addCommand(&_command);
}
void Test::onDraw()
{
//clear everything
glClearColor(0, 0, 0, 1);
glClear(GL_COLOR_BUFFER_BIT);
//bind the program (the shaders)
_glProgram->use();
//bind the texture and set the "tex" uniform in the fragment shader
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, TEXTUREID);
GLuint tex = glGetUniformLocation(_glProgram->getProgram(), "tex");
glUniform1i(tex, 0);
//bind the vao
glBindVertexArray(_vao);
//draw the vao
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
}
新建Test.h，代码如下：
//
// Test.h
// Texture
//
// Created by zhufu on 2017/3/28.
//
//
#ifndef Test_h
#define Test_h
#include <stdio.h>
USING_NS_CC;
class Test : public Node
{
public:
enum Format {
Format_Grayscale = 1, /**< one channel: grayscale */
Format_GrayscaleAlpha = 2, /**< two channels: grayscale and alpha */
Format_RGB = 3, /**< three channels: red, green, blue */
Format_RGBA = 4 /**< four channels: red, green, blue, alpha */
};
static Test* create();
virtual bool init() override;
virtual void draw(Renderer* renderer, const Mat4 &transform, uint32_t platform) override;
void onDraw();
void loadShader();
void loadTexture();
void loadRectangle();
void initCommand();
void flipVertical(int width, int height, unsigned char* arr);
private:
GLuint TEXTUREID;
GLProgram* _glProgram;
GLuint _vao;
CustomCommand _command;
};
#endif /* Test_h */
如图：
修改HelloWorldScene.cpp，
先
include "Test.h"再修改CreateScene方法：
Scene* HelloWorld::createScene()
{
// 'scene' is an autorelease object
auto scene = Scene::create();
auto test = Test::create();
scene->addChild(test);
// 'layer' is an autorelease object
auto layer = HelloWorld::create();
// add layer as a child to scene
scene->addChild(layer);
// return the scene
return scene;
}
在Resources方位夹下新建shader文件夹，再在shader新建myVertexShader.vsh和myFragmentShader.fsh文件。
如图：
myVertexShader.vsh
attribute vec3 vert;
attribute vec2 vertTexCoord;
varying vec2 textureOut;
void main() {
// Pass the tex coord straight through to the fragment shader
textureOut = vertTexCoord;
gl_Position = vec4(vert, 1);
}
myFragmentShader.fsh
uniform sampler2D tex;
varying vec2 textureOut;
void main() {
gl_FragColor = texture2D(tex, textureOut);
}
修改成：
接下来，可以开心地运行程序了。
运行效果：
