GLerror

#include "GLTriangle.h"

#include "SimpleGlFuncs.h"


static const char gVertexShader[] =
    "attribute vec4 vPosition;\n"
        "attribute vec4 vColor;\n"
        "\n"
        "varying mediump vec4 fColor;"
        "\n"
    "void main() {\n"
    "  gl_Position = vPosition;\n"
        "  fColor = vColor;\n"
    "}\n";

static const char gFragmentShader[] =
    "precision mediump float;\n"
        "\n"
        "varying mediump vec4 fColor;\n"
        "\n"
    "void main() {\n"
    "  gl_FragColor = fColor;\n"
    "}\n";

static const GLfloat gTriangleVertices[] = {
                 0.0f,  0.9f, 0.0f,
                -0.9f, -0.9f, 0.0f,
         0.9f, -0.9f,  0.0f,

         0.0f, 0.5f,  0.5f,
         0.5f, 0.5f, 0.0f,
         0.5f, 0.5f, 0.0f,
};

GLTriangle::GLTriangle() {
        m_program = createProgram(gVertexShader, gFragmentShader);

        m_position = glGetAttribLocation(m_program, "vPosition");
        checkGlError("glGetAttribLocation");
        LOGI("glGetAttribLocation(\"vPosition\") = %d\n",
                        m_position);

        m_color = glGetAttribLocation(m_program, "vColor");
        checkGlError("glGetAttribLocation(vColor)");
        LOGI("glGetAttribLocation(\"vColor\") = %d\n",
                        m_color);

        this->bufferSetup();
}

GLTriangle::~GLTriangle() {
        // TODO Auto-generated destructor stub
}

void GLTriangle::bufferSetup()
{
        glUseProgram(m_program);
        checkGlError("GLTriangle::bufferSetup glUseProgram(m_program);");

        {
                glGenBuffers(1,&m_buffer);
                checkGlError("GLTriangle::bufferSetup glGenBuffers");

                glBindBuffer(GL_ARRAY_BUFFER,m_buffer);
                checkGlError("GLTriangle::bufferSetup glBufferData");

                glBufferData(GL_ARRAY_BUFFER,sizeof(float)*(3+3)*3,gTriangleVertices,GL_DYNAMIC_DRAW);
                checkGlError("GLTriangle::bufferSetup glBufferData");
        }



}

void GLTriangle::setA(const float* xyz)
{
    glBindBuffer(GL_ARRAY_BUFFER,m_buffer);
    checkGlError("GLTriangle::setA glBindBuffer");

    glBufferSubData(GL_ARRAY_BUFFER,sizeof(float)*0*3 ,sizeof(float)*3,xyz);
    checkGlError("GLTriangle::setA glBufferSubData");
}

void GLTriangle::setB(const float* xyz)
{
    glBindBuffer(GL_ARRAY_BUFFER,m_buffer);
    glBufferSubData(GL_ARRAY_BUFFER,sizeof(float)*1*3,sizeof(float)*3,xyz);
}

void GLTriangle::setC(const float* xyz)
{
    glBindBuffer(GL_ARRAY_BUFFER,m_buffer);
    glBufferSubData(GL_ARRAY_BUFFER,sizeof(float)*2*3,sizeof(float)*3,xyz);
}


void GLTriangle::draw()
{
    checkGlError("Start GLTriangle::draw()");


    glUseProgram(m_program);
    checkGlError("glUseProgram");


    glBindBuffer(GL_ARRAY_BUFFER,m_buffer);
    checkGlError("GLTriangle::draw glBindBuffer");

    {
      glVertexAttribPointer(m_position, 3, GL_FLOAT, GL_FALSE, 0, 0);
      checkGlError("GLTriangle::bufferSetup glVertexAttribPointer(gvPositionHandle,...");

      glEnableVertexAttribArray(m_position);
      checkGlError("GLTriangle::bufferSetup glEnableVertexAttribArray(gvPositionHandle);");

      glVertexAttribPointer(m_color, 3, GL_FLOAT, GL_FALSE, 0, (void*) (3*3*sizeof(float)) );
      checkGlError("GLTriangle::bufferSetup glVertexAttribPointer(gvColorHandler,...");

      glEnableVertexAttribArray(m_color);
      checkGlError("GLTriangle::bufferSetup glEnableVertexAttribArray(gvColorHandler);");
    }


    glDrawArrays(GL_TRIANGLES, 0, 3);
    checkGlError("GLTriangle::draw glDrawArrays");
}