Cocos2dx CCRenderTexture - OpenGL ES2未呈现

Question

我试图在Cocos2dx 2，OpenGL ES2中为纹理添加渐变。 但是OpenGL内容没有得到渲染。

这个代码是基于教程链接： http://www.raywenderlich.com/3857/how-to-create-dynamic-textures-with-ccrendertexture

CCRenderTexture *rt = CCRenderTexture::create((int)textureSize, (int)textureSize); 
rt->beginWithClear(bgColor.r, bgColor.g, bgColor.b, bgColor.a); 

float gradientAlpha = 0.5; 
CCPoint vertices[4]; 
ccColor4F colors[4]; 
int nVertices = 0; 

vertices[nVertices] = CCPointMake(0, 0); 
colors[nVertices++] = ccc4f(0, 0, 0, 0); 
vertices[nVertices] = CCPointMake(textureSize, 0); 
colors[nVertices++] = ccc4f(0, 0, 0, 0); 
vertices[nVertices] = CCPointMake(0, textureSize); 
colors[nVertices++] = ccc4f(0, 0, 0, gradientAlpha); 
vertices[nVertices] = CCPointMake(textureSize, textureSize); 
colors[nVertices++] = ccc4f(0, 0, 0, gradientAlpha); 

// Set the shader program for OpenGL 
setShaderProgram(CCShaderCache::sharedShaderCache()->programForKey(kCCShader_PositionColor)); 
CC_NODE_DRAW_SETUP(); 

glVertexAttribPointer(kCCVertexAttrib_Position, 2, GL_FLOAT, GL_FALSE, 0, vertices); 
glVertexAttribPointer(kCCVertexAttrib_Color, 4, GL_FLOAT, GL_FALSE, 0, colors); 
ccGLBlendFunc(CC_BLEND_SRC, CC_BLEND_DST); 
glDrawArrays(GL_TRIANGLE_STRIP, 0, (GLsizei)nVertices); 

CCSprite* noise = CCSprite::create("Noise.png"); 
ccBlendFunc blendFunc; 
blendFunc.src = GL_DST_COLOR; 
blendFunc.dst = GL_ZERO; 
noise->setBlendFunc(blendFunc); 
noise->setPosition(ccp(textureSize/2, textureSize/2)); 
noise->visit(); 

rt->end(); 
return CCSprite::createWithTexture(rt->getSprite()->getTexture()); 

请让我知道如果我做错了什么。谢谢。

Answer 1

看来我们已经使用ccVertex2F代替CCPoint作为顶点。

此外，绘制渐变并不明确需要混合函数。

这里是更新的C++代码：

float gradientAlpha = 0.5; 
ccVertex2F vertices[4]; 
ccColor4F colors[4]; 
int nVertices = 0; 

vertices[nVertices] = vertex2(0, 0); 
colors[nVertices++] = ccc4f(0, 0, 0, 0); 
vertices[nVertices] = vertex2(textureSize, 0); 
colors[nVertices++] = ccc4f(0, 0, 0, 0); 
vertices[nVertices] = vertex2(0, textureSize); 
colors[nVertices++] = ccc4f(0, 0, 0, gradientAlpha); 
vertices[nVertices] = vertex2(textureSize, textureSize); 
colors[nVertices++] = ccc4f(0, 0, 0, gradientAlpha); 

// Set the shader program for OpenGL 
setShaderProgram(CCShaderCache::sharedShaderCache()->programForKey(kCCShader_PositionColor)); 
CC_NODE_DRAW_SETUP(); 

ccGLEnableVertexAttribs(kCCVertexAttribFlag_Position | kCCVertexAttribFlag_Color); 

glVertexAttribPointer(kCCVertexAttrib_Position, 2, GL_FLOAT, GL_FALSE, 0, vertices); 
glVertexAttribPointer(kCCVertexAttrib_Color, 4, GL_FLOAT, GL_FALSE, 0, colors); 

glDrawArrays(GL_TRIANGLE_STRIP, 0, (GLsizei)nVertices); 

Answer 2

我不是很肯定这怎么工作的，但如果你只是想用渐变色的东西，你可以尝试或检查CCLayerGradient的源代码， 这里是链接http://www.cocos2d-x.org/reference/native-cpp/d9/d19/classcocos2d_1_1_c_c_layer_gradient.html