glDrawArrays with cocos2d not drawing at all - c++

Question

I have a lot of points that i need to draw in a batch and i have been trying it for two days and i cant seem get any progress with glDrawArrays. I have tried DrawNode and drawing each individual point for testing and it works correctly... but i cant seem to get glDrawArray to give any visual result.
Here is my drawing code(changed a few variable names):
auto glProgram = getGLProgram();
if (glProgram == nullptr) {
setGLProgramState(GLProgramState::getOrCreateWithGLProgramName(
GLProgram::SHADER_NAME_POSITION_COLOR));
glProgram = getGLProgram();
if (glProgram == nullptr) {
return;
}
}
glProgram->use();
glProgram->setUniformsForBuiltins();
GL::enableVertexAttribs(GL::VERTEX_ATTRIB_FLAG_POSITION | GL::VERTEX_ATTRIB_FLAG_COLOR);
GLfloat *vertices = new GLfloat[myStruct->data.size()*2];
GLfloat *colors = new GLfloat[myStruct->data.size()*4];
int vIndex = 0;
int cIndex = 0;
for (std::vector<myPointStruct*>::iterator it = myStruct->data.begin(); it != myStruct->data.end(); ++it) {
vertices[vIndex++] = (*it)->pos.x;
vertices[vIndex++] = (*it)->pos.y;
colors[cIndex++] = (*it)->color.r;
colors[cIndex++] = (*it)->color.g;
colors[cIndex++] = (*it)->color.b;
colors[cIndex++] = (*it)->color.a;
glLineWidth(10);
glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_POSITION, 2, GL_FLOAT, GL_FALSE, sizeof(GLfloat), &vertices[0]);
glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_COLOR, 4, GL_FLOAT, GL_FALSE, sizeof(GLfloat), &colors[0]);
glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
glDrawArrays(GL_POINTS, 0, (GLsizei) myStruct->data.size());
CC_INCREMENT_GL_DRAWN_BATCHES_AND_VERTICES(1, (GLsizei) myStruct->data.size());
And here is how i call the method:
_renderTexture->begin();
myMethodForDrawing();
_renderTexture->end();
Director::getInstance()->getRenderer()->render();
I have also tried:
_renderTexture->begin();
_customCommand.init(_renderTexture->getGlobalZOrder());
_customCommand.func = CC_CALLBACK_0(MyClass:: myMethodForDrawing,this);
auto renderer = Director::getInstance()->getRenderer();
renderer->addCommand(&_customCommand);
_renderTexture->end();

Answer 1

The 5th paramter of glVertexAttribPointer specifies the byte offset between consecutive generic vertex attributes. If stride is 0, the generic vertex attributes are understood to be tightly packed in the array.
Since your vertices and colors are tightly packed, you do not need to set the stride parameter. Note, sizeof(GLfloat) is wrong anyway. In you case it would be 2 * sizeof(GLfloat) for vertices and 4 * sizeof(GLfloat) for colors.
Change your code like this (focus on the 0 for the 5th parameter):
glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_POSITION, 2, GL_FLOAT, GL_FALSE, 0, &vertices[0]);
glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_COLOR, 4, GL_FLOAT, GL_FALSE, 0, &colors[0]);