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本节主要讲利用cocos2dx机制实现opengl es shader脚本的绘制
这里先看下最终效果:
这里分别实现了灰度效果及残影的效果。
一、绘制基类
这里主要参考了cocos2dx源码中 RenderTexture 的实现，有兴趣的可以了解下。
绘制基类RenderShader主要实现以下方法:
//****************************************************************** // 文件名: RenderShader.h // 创建人: 稀饭lei // 版 本: 1.0 // 描 述: 特效基类 //****************************************************************** #ifndef _RenderShader_H__ #define _RenderShader_H__ #include "cocos2d.h" USING_NS_CC; // GL纹理坐标组 static const GLfloat ccRenderTextcord[8] ={ 0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, }; class RenderShader : public Node { public: static RenderShader* create(); virtual bool LoadByteArray(const GLchar* vShaderByteArray, const GLchar* fShaderByteArray); //加载 shader文件 void begin(); // 用于设置绘制开始要调用的onBegin void end(); // 用于设置绘制结束要调用的onEnd void push2Draw(Node* node); // 添加待绘制节点 virtual void draw(Renderer *renderer, const Mat4 &transform, uint32_t flags) override; // cocos2dx绘制回调 protected: virtual void onBegin(); virtual void onEnd(); //virtual void onClear(); virtual void Render(); // 绘制实现 virtual bool init(); virtual void CreateFrameBuffer(); //创建FBO及texture RenderShader(void); virtual ~RenderShader(void); GLuint m_nFrameBuffer; // 用于当前绘制的fbo GLuint m_nFrameBufferTexture; // 用于绑定在fbo中的texture GLProgram* m_glprogram; // GL绘制管理 GLint m_nOldFBO; // 原来的fbo CustomCommand _beginCommand; CustomCommand _endCommand; GroupCommand _groupCommand; std::set<Node*> sRenderChild; // 需要绘制的节点 Size m_sRenderSize; }; #endif
这里有几个主要实现：
1、我们用push2Draw(Node* node); 方法将待绘制的节点添加到sRenderChild中等待处理。
2、参考RenderTexture 的实现，我们也利用begin,end将需要绘制的节点利用visit访问添加到当前的RenderShader类所在的render层中进行绘制。
3、在实际绘制过程中调用的onBegin中缓存对应的坐标系，同时绑定我们创建的FBO使得visit进来的节点可以绘制到当前FBO中。然后在onEnd中调用render方法将我们的FBO内容绘制原来cocos2dx底层的FBO上。
4、在render()实现如何绘制当前FBO的内容到cocos2dx的FBO上。（实际shader作业的地方）
详细实现代码如下:
#include "RenderShader.h" #define STRINGIFY(A) #A const char* ccPositionTextureColor_frag_test = STRINGIFY( \n#ifdef GL_ES\n precision lowp float; \n#endif\n varying vec4 v_fragmentColor; varying vec2 v_texCoord; void main() { vec4 color = v_fragmentColor * texture2D(CC_Texture0, v_texCoord); float gray = dot(color.rgb, vec3(0.299, 0.587, 0.114)); gl_FragColor = vec4(vec3(gray), color.a); } ); RenderShader* RenderShader::create() { auto node = new RenderShader(); if (node && node->init()) { node->autorelease(); return node; } delete node; return nullptr; } bool RenderShader::init() { if (m_glprogram) { m_glprogram->release(); m_glprogram = nullptr; } CreateFrameBuffer(); m_glprogram = GLProgram::createWithByteArrays(ccPositionTextureColor_noMVP_vert, ccPositionTextureColor_frag_test); m_glprogram->retain(); return true; } RenderShader::RenderShader(void) :m_nFrameBuffer(0), m_nFrameBufferTexture(0), m_glprogram(nullptr) { GLView* glView = Director::getInstance()->getOpenGLView(); if (!glView) { return; } //屏幕大小 m_sRenderSize = glView->getFrameSize(); } RenderShader::~RenderShader(void) { if (m_glprogram) { m_glprogram->release(); m_glprogram = nullptr; } if (m_nFrameBuffer) { glDeleteFramebuffers(1, &m_nFrameBuffer); m_nFrameBuffer = 0; } if (m_nFrameBufferTexture) { glDeleteTextures(1, &m_nFrameBufferTexture); m_nFrameBufferTexture = 0; } } bool RenderShader::LoadByteArray(const GLchar* vShaderByteArray, const GLchar* fShaderByteArray) { if (m_glprogram) { m_glprogram->release(); m_glprogram = nullptr; } this->CreateFrameBuffer(); m_glprogram = GLProgram::createWithByteArrays(vShaderByteArray, fShaderByteArray); m_glprogram->retain(); return true; } void RenderShader::onBegin() { if (!m_nFrameBuffer) { return; } Director* director = Director::getInstance(); director->pushMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_PROJECTION); director->pushMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW); //save old fbo and bind own glGetIntegerv(GL_FRAMEBUFFER_BINDING, &m_nOldFBO); glBindFramebuffer(GL_FRAMEBUFFER, m_nFrameBuffer); glClearColor(0.0, 0.0, 0.0, 0.0); glClear(GL_COLOR_BUFFER_BIT); } void RenderShader::onEnd() { if (!m_nFrameBuffer) { return; } // restore viewport for render to direct fbo Director *director = Director::getInstance(); // restore viewport director->setViewport(); this->Render(); glBindFramebuffer(GL_FRAMEBUFFER, m_nOldFBO); director->popMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_PROJECTION); director->popMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW); } void RenderShader::Render() { if (!m_glprogram || !m_nFrameBufferTexture) { return; } glBindFramebuffer(GL_FRAMEBUFFER, m_nOldFBO); m_glprogram->use(); m_glprogram->setUniformsForBuiltins(); //GLuint glTexture = m_glprogram->getUniformLocationForName("CC_Texture0"); //glActiveTexture(GL_TEXTURE0); //glBindTexture(GL_TEXTURE_2D, m_nFrameBufferTexture); //glUniform1i(glTexture, 0); GL::bindTexture2D(m_nFrameBufferTexture); Size sSize = Director::getInstance()->getVisibleSize(); float x = 0; float y = 0; float w = sSize.width; float h = sSize.height; GLfloat vertices[] = { x, y + h, x + w, y + h, x, y, x + w, y }; glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_POSITION, 2, GL_FLOAT, GL_FALSE, 0, vertices); glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_TEX_COORD, 2, GL_FLOAT, GL_FALSE, 0, ccRenderTextcord); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); /*GL::bindVAO(0); glBindBuffer(GL_ARRAY_BUFFER, 0); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);*/ } void RenderShader::CreateFrameBuffer() { glGetIntegerv(GL_FRAMEBUFFER_BINDING, &m_nOldFBO); if (m_nFrameBuffer == 0) { glGenFramebuffers(1, &m_nFrameBuffer); if (m_nFrameBuffer == 0) { CCLOG("m_FilterFrameBuffer == 0"); return; } } glBindFramebuffer(GL_FRAMEBUFFER, m_nFrameBuffer); if (m_nFrameBufferTexture == 0) { glGenTextures(1, &m_nFrameBufferTexture); glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, m_nFrameBufferTexture); GLsizei nWidth = m_sRenderSize.width; GLsizei nHeight = m_sRenderSize.height; 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, nWidth, nHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0); GLenum err = glGetError(); if (err != GL_NO_ERROR) { CCLOG("cocos2d: Texture2D: Error uploading compressed texture glError: 0x%04X", err); return; } } glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_nFrameBufferTexture, 0); GLenum error; if ((error = glCheckFramebufferStatus(GL_FRAMEBUFFER)) != GL_FRAMEBUFFER_COMPLETE) { CCLOG("Failed to make complete framebuffer object 0x%X", error); return; } glBindFramebuffer(GL_FRAMEBUFFER, m_nOldFBO); } void RenderShader::begin() { Director* director = Director::getInstance(); CCASSERT(nullptr != director, "Director is null when seting matrix stack"); director->pushMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_PROJECTION); director->pushMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW); _groupCommand.init(_globalZOrder); Renderer *renderer = Director::getInstance()->getRenderer(); renderer->addCommand(&_groupCommand); renderer->pushGroup(_groupCommand.getRenderQueueID()); _beginCommand.init(_globalZOrder); _beginCommand.func = CC_CALLBACK_0(RenderShader::onBegin, this); renderer->addCommand(&_beginCommand); } void RenderShader::end() { _endCommand.init(_globalZOrder); _endCommand.func = CC_CALLBACK_0(RenderShader::onEnd, this); Director* director = Director::getInstance(); CCASSERT(nullptr != director, "Director is null when seting matrix stack"); Renderer *renderer = director->getRenderer(); renderer->addCommand(&_endCommand); renderer->popGroup(); director->popMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_PROJECTION); director->popMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW); } void RenderShader::draw(Renderer *renderer, const Mat4 &transform, uint32_t flags) { //Begin will create a render group using new render target begin(); ////clear screen //_clearCommand.init(_globalZOrder); //_clearCommand.func = CC_CALLBACK_0(RenderShader::onClear, this); //renderer->addCommand(&_clearCommand); //! make sure all children are drawn { auto it = sRenderChild.begin(); while (it != sRenderChild.end()) { if (Node* node = *it) { node->visit(renderer, transform, flags); node->release(); } ++it; } sRenderChild.clear(); } //End will pop the current render group end(); } void RenderShader::push2Draw(Node* node) { if (node && sRenderChild.find(node) == sRenderChild.end()) { node->retain(); sRenderChild.insert(node); } else { CCLOG(" push same!!!"); } }
这里shader代码实现的是灰度图的效果，其他效果可以自己修改ccPositionTextureColor_frag_test内容。
二、实际使用
1、将RenderShader当成正常的Node使用，设置父节点及index坐标等。
m_pShader = RenderShader::create(); this->addChild(m_pShader);
2、因为RenderShader在draw中对需要绘制的子节点进行了清理，所以需要每次重新对子节点进行添加，添加动画节点如下:
void CPlayer::draw(Renderer *renderer, const Mat4 &transform, uint32_t flags) { if (m_pShader) { m_pShader->push2Draw(m_pNode); } }
主要事项:RenderShader在Render方法中将内容绘制到原来的FBO中，而cocos2dx对每个需要绘制的同一index层级会在开始的时候单独创建一个FBO来处理。因而如果RenderShader单独一个层级可能导致此时的FBO没有创建，导致没有绘制效果。
到这里我们就实现灰色角色的效果了，使用也依照cocos2dx的用法，相对简单。
三、残影效果扩展
主要实现代码如下:
//****************************************************************** // 文件名: RemindShader.h // 创建人: 稀饭lei // 版 本: 1.0 // 描 述: 残影特效 //****************************************************************** #ifndef _RemindShader_H__ #define _RemindShader_H__ #include "RenderShader.h" USING_NS_CC; #define REMIND_RENDER_COUNT 5 // 残影个数 class RemindShader :public RenderShader { public: static RemindShader* create(); virtual void draw(Renderer *renderer, const Mat4 &transform, uint32_t flags) override; private: virtual void onBegin() override; //virtual void onClear(); virtual void Render() override; virtual bool init() override; virtual void CreateFrameBuffer() override; RemindShader(void); virtual ~RemindShader(void); GLuint m_pTextureArr[REMIND_RENDER_COUNT]; int m_nRenderFrq; // 渲染间隔帧率 int m_nRenderCount; // 渲染间隔计数 int m_nCurTexutreIndex; // 当前渲染的纹理ID }; #endif #include "RemindShader.h" #define STRINGIFY(A) #A const char* ccRemind_fsh = STRINGIFY( \n#ifdef GL_ES\n precision lowp float; \n#endif\n varying vec2 v_texCoord; uniform float u_alpha; void main() { vec4 pcolor = texture2D(CC_Texture0, v_texCoord) * u_alpha; gl_FragColor = pcolor; } ); RemindShader* RemindShader::create() { auto node = new RemindShader(); if (node && node->init()) { node->autorelease(); return node; } delete node; return nullptr; } bool RemindShader::init() { if (m_glprogram) { m_glprogram->release(); m_glprogram = nullptr; } CreateFrameBuffer(); m_glprogram = GLProgram::createWithByteArrays(ccPositionTextureColor_noMVP_vert, ccRemind_fsh); m_glprogram->retain(); return true; } RemindShader::RemindShader(void) : m_nCurTexutreIndex(0), m_nRenderFrq(10), m_nRenderCount(0) { memset(m_pTextureArr, 0, REMIND_RENDER_COUNT); } RemindShader::~RemindShader(void) { if (m_pTextureArr[0]) { glDeleteTextures(REMIND_RENDER_COUNT, m_pTextureArr); memset(m_pTextureArr, 0, REMIND_RENDER_COUNT); } } void RemindShader::onBegin() { if (!m_nFrameBuffer) { return; } Director* director = Director::getInstance(); director->pushMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_PROJECTION); director->pushMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW); // director->setProjection(director->getProjection()); // GLView* glView = director->getOpenGLView(); // if (!glView) // { // return; // } // Size frameSize =glView->getFrameSize(); // { // // Calculate the adjustment ratios based on the old and new projections // Size size = director->getWinSizeInPixels(); // float widthRatio = size.width / frameSize.width; // float heightRatio = size.height / frameSize.height; // //caculate the projections of size change // Mat4 orthoMatrix; // Mat4::createOrthographicOffCenter((float)-1.0 / widthRatio, (float)1.0 / widthRatio, (float)-1.0 / heightRatio, (float)1.0 / heightRatio, -1, 1, &orthoMatrix); // director->multiplyMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_PROJECTION, orthoMatrix); // } // // //calculate viewport // { // glViewport(0, 0, (GLsizei)(frameSize.width), (GLsizei)(frameSize.height)); // } glGetIntegerv(GL_FRAMEBUFFER_BINDING, &m_nOldFBO); // 仅在计数为0才更新新的渲染 if (m_nRenderCount == 0) { glBindFramebuffer(GL_FRAMEBUFFER, m_nFrameBuffer); glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_pTextureArr[m_nCurTexutreIndex], 0); m_nCurTexutreIndex = m_nCurTexutreIndex + 1 < REMIND_RENDER_COUNT ? m_nCurTexutreIndex + 1 : 0; glClearColor(0.0, 0.0, 0.0, 0.0); glClear(GL_COLOR_BUFFER_BIT); } } void RemindShader::Render() { if (!m_glprogram ) { return; } glBindFramebuffer(GL_FRAMEBUFFER, m_nOldFBO); m_glprogram->use(); m_glprogram->setUniformsForBuiltins(); Size sSize = Director::getInstance()->getVisibleSize(); float x = 0; float y = 0; float w = sSize.width; float h = sSize.height; // 除当前纹理外的纹理存储的都是拖影 int nBeginIndex = m_nCurTexutreIndex; int nCurIndex = nBeginIndex; GLfloat falpha = 0.3f; float addf = 0.05f; // 渲染存在m_pTextureArr队列里的拖影纹理到主场景 do { Point delta = _position;// this->convertToWorldSpace(_position); GLfloat vertices[] = { x - delta.x,y+ h - delta.y, x+w - delta.x,y+ h - delta.y, x - delta.x , y - delta.y, x+w - delta.x, y - delta.y }; //GLuint glTexture = m_glprogram->getUniformLocationForName("CC_Texture0"); //glActiveTexture(GL_TEXTURE0); //glBindTexture(GL_TEXTURE_2D, m_pTextureArr[nCurIndex]); //glUniform1i(glTexture, 0); GL::bindTexture2D(m_pTextureArr[nCurIndex]); GLuint glAlpha = m_glprogram->getUniformLocationForName("u_alpha"); glUniform1f(glAlpha, falpha); glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_POSITION, 2, GL_FLOAT, GL_FALSE, 0, vertices); glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_TEX_COORD, 2, GL_FLOAT, GL_FALSE, 0, ccRenderTextcord); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); falpha += addf; addf += 0.025f; nCurIndex = ++nCurIndex<REMIND_RENDER_COUNT ? nCurIndex : 0; } while (nCurIndex != nBeginIndex); // // GL::bindVAO(0); //glBindBuffer(GL_ARRAY_BUFFER, 0); //glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0); } void RemindShader::CreateFrameBuffer() { glGetIntegerv(GL_FRAMEBUFFER_BINDING, &m_nOldFBO); if (m_nFrameBuffer == 0) { glGenFramebuffers(1, &m_nFrameBuffer); if (m_nFrameBuffer == 0) { CCLOG("m_FilterFrameBuffer == 0"); return; } } GLsizei nWidth = m_sRenderSize.width; GLsizei nHeight = m_sRenderSize.height; glBindFramebuffer(GL_FRAMEBUFFER, m_nFrameBuffer); if (m_pTextureArr[0] == 0) { glGenTextures(REMIND_RENDER_COUNT, m_pTextureArr); for (int i = 0; i < REMIND_RENDER_COUNT; i++) { glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, m_pTextureArr[i]); 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, nWidth, nHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0); GLenum err = glGetError(); if (err != GL_NO_ERROR) { CCLOG("cocos2d: Texture2D: Error uploading compressed texture glError: 0x%04X", err); return; } glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_pTextureArr[i], 0); glClearColor(0.0, 0.0, 0.0, 0.0); glClear(GL_COLOR_BUFFER_BIT); } } glBindFramebuffer(GL_FRAMEBUFFER, m_nOldFBO); } void RemindShader::draw(Renderer *renderer, const Mat4 &transform, uint32_t flags) { if (sRenderChild.size() <= 0 ) { if (m_nFrameBuffer) { // 清理所有缓存的纹理 glGetIntegerv(GL_FRAMEBUFFER_BINDING, &m_nOldFBO); glBindFramebuffer(GL_FRAMEBUFFER, m_nFrameBuffer); for (int i = 0; i < REMIND_RENDER_COUNT; i++) { glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_pTextureArr[i], 0); glClearColor(0.0, 0.0, 0.0, 0.0); glClear(GL_COLOR_BUFFER_BIT); } glBindFramebuffer(GL_FRAMEBUFFER, m_nOldFBO); } m_nRenderCount = m_nRenderFrq - 1; return; } //Begin will create a render group using new render target begin(); if (++m_nRenderCount == m_nRenderFrq) { //! make sure all children are drawn auto it = sRenderChild.begin(); while (it != sRenderChild.end()) { if (Node* node = *it) { node->visit(renderer, transform, flags); node->release(); } ++it; } m_nRenderCount = 0; // 0 提示需要渲染进去 } sRenderChild.clear(); //End will pop the current render group end(); }
几个关键点:
1、利用REMIND_RENDER_COUNT控制需要创建的Texture个数，通过每次绘制到不同的Texture上来保存原来的效果。
2、shader中利用u_alpha参数控制残影的透明度，在render中绘制到原来的FBO上时调用不同的透明度来实现残影渐隐的效果。
3、通过m_nRenderFrq来控制间隔的绘制次数，来实现残影的残留效果远近。
这样就实现了残影的效果了，使用的方法还是跟基类一样。
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原文地址：http://www.cnblogs.com/stratrail/p/5072632.html
