And my shader setup
vertexSrc = "attribute vec4 position; attribute vec4 inputTextureCoordinate; varying vec2 textureCoordinate; void main() { gl_Position = position; textureCoordinate = inputTextureCoordinate.xy;}";
fragmentSrc = "varying highp vec2 textureCoordinate; uniform sampler2D videoFrame; precision mediump float; void main() { gl_FragColor = texture2D(videoFrame, textureCoordinate); }";
//Position of the triangle (x,y,z) why 4 D:!
//the value is for example, 0.4f is 40% of the glViewPort.
float size = 1.0f;
vertexArray[0] = -size; vertexArray[1] = size; vertexArray[2] = 0.0f;
vertexArray[3] = -size; vertexArray[4] = -size; vertexArray[5] = 0.0f;
vertexArray[6] = size; vertexArray[7] = -size; vertexArray[8] = 0.0f;
vertexArray[9] = size; vertexArray[10] = size; vertexArray[11] = 0.0f;
// Get dimensions from IwGL
int w = SCREEN_WIDTH;
int h = SCREEN_HEIGHT;
//Set the place where we will draw, in this case is a rectangle of wxh with starting position at (0,0).
glViewport(0, 0, w, h) ;
glClearColor(0, 0, 0, 1);
//Create a program to attach vertex and fragments shaders (Source code) to it.
GLuint shaderProgram = glCreateProgram();
//Loading source codes.
GLuint vertexShader = createShader(GL_VERTEX_SHADER, vertexSrc);
GLuint fragmentShader = createShader(GL_FRAGMENT_SHADER, fragmentSrc);
//Attach a source code to the whole program (ShaderProgram)
glAttachShader(shaderProgram, vertexShader);
glAttachShader(shaderProgram, fragmentShader);
//Set the location of the "position" variable defined before.
//If I remove this, the code works exactly the same way. I think OpenGL set por default
//to 0 the first variable in the code.
glBindAttribLocation(shaderProgram, 0, "position");
//Linking phase, create a whole functionally program with all attached shaders.
glLinkProgram(shaderProgram);
//It's like executing a .exe in windows.
glUseProgram(shaderProgram);
