I want to obtain color ramp effect from this tutorial: http://www.raywenderlich.com/10862/how-to-create-cool-effects-with-custom-shaders-in-opengl-es-2-0-and-cocos2d-2-x
Here is my code in cocos2d-x 3:
bool HelloWorld::init()
{
//////////////////////////////
// 1. super init first
if ( !Layer::init() )
{
return false;
}
Vec2 origin = Director::getInstance()->getVisibleOrigin();
sprite = Sprite::create("HelloWorld.png");
sprite->setAnchorPoint(Vec2(0, 0));
sprite->setRotation(3);
sprite->setPosition(origin);
addChild(sprite);
std::string str = FileUtils::getInstance()->getStringFromFile("CSEColorRamp.fsh");
const GLchar * fragmentSource = str.c_str();
GLProgram* p = GLProgram::createWithByteArrays(ccPositionTextureA8Color_vert, fragmentSource);
p->bindAttribLocation(GLProgram::ATTRIBUTE_NAME_POSITION, GLProgram::VERTEX_ATTRIB_POSITION);
p->bindAttribLocation(GLProgram::ATTRIBUTE_NAME_TEX_COORD, GLProgram::VERTEX_ATTRIB_TEX_COORD);
p->link();
p->updateUniforms();
sprite->setGLProgram(p);
// 3
colorRampUniformLocation = glGetUniformLocation(sprite->getGLProgram()->getProgram(), "u_colorRampTexture");
glUniform1i(colorRampUniformLocation, 1);
// 4
colorRampTexture = Director::getInstance()->getTextureCache()->addImage("colorRamp.png");
colorRampTexture->setAliasTexParameters();
// 5
sprite->getGLProgram()->use();
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, colorRampTexture->getName());
glActiveTexture(GL_TEXTURE0);
return true;
}
And here is the fragment shader as it is in the tutorial:
#ifdef GL_ES
precision mediump float;
#endif
// 1
varying vec2 v_texCoord;
uniform sampler2D u_texture;
uniform sampler2D u_colorRampTexture;
void main()
{ // 2
vec3 normalColor = texture2D(u_texture, v_texCoord).rgb;
// 3
float rampedR = texture2D(u_colorRampTexture, vec2(normalColor.r, 0)).r;
float rampedG = texture2D(u_colorRampTexture, vec2(normalColor.g, 0)).g;
float rampedB = texture2D(u_colorRampTexture, vec2(normalColor.b, 0)).b;
// 4
gl_FragColor = vec4(rampedR, rampedG, rampedB, 1);
}
As a result I get a black screen with 2 draw calls. What is wrong? Do I miss something?
