cocos2d V3 glDrawArrays not working

Question

Converting to cocos2d V3 and this code produces no drawing:

[_shaderProgram use]; //for V2 this was [shaderProgram_ use];

ccGLEnableVertexAttribs(kCCVertexAttribFlag_Position | kCCVertexAttribFlag_Color);
glVertexAttribPointer(kCCVertexAttrib_Position, 2, GL_FLOAT, GL_FALSE, 0, lineVertices);
glVertexAttribPointer(kCCVertexAttrib_Color, 4, GL_FLOAT, GL_FALSE, 0, colorVertices);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

glDrawArrays(GL_TRIANGLE_STRIP, 0, 6);

Why does this code not work in V3? This code is called from the draw method of a CCScene. Any help much appreciated.

UPDATE: partial workaround found by calling ccDrawPoint before this code (drawing a small random point). Then glDrawArrays draws the correct shape (reading my lineVertices array) but ignores my colorVertices array. How can I get glDrawArrays to use my colorVertices array? (this code was working before I converted to V3)

Answer 1

I've been doing a bit of GL drawing on nodes recently, and had similar issues until I dug into the drawing code of CCNode.

Instead of explicitly calling use on the shaderProgram, try to call the following macro:

CC_NODE_DRAW_SETUP()

It expands to essentially the following in Cocos2D v3:

ccGLEnable(_glServerState);
[_shaderProgram use];
[_shaderProgram setUniformsForBuiltins];