#pragma once
//Disable string safety warning
#pragma warning(disable:4996)

//STD
#include <stdio.h>
#include <iostream>
#include <assert.h>

//GL
#include <GLee5_4/GLee.h>
#include <gl/gl.h>
#include <gl/glu.h>
#include <gl/glut.h>

//SDL
#include <SDL.h>
#include <SDL_opengl.h>

static const char* const sourceVert =
    "void main() {\n"
    "   gl_Position = gl_Vertex + vec4(0.5);\n"
    "}";

static void checkShader(const GLuint id, const GLenum type, const char str[])   {
    static char msg[240];
    int size,aux;
    glGetObjectParameterivARB(id, type, &size);
    if(!size) return;
    glGetObjectParameterivARB(id, GL_OBJECT_INFO_LOG_LENGTH_ARB, &size);
    assert(size < sizeof(msg));
    glGetInfoLogARB(id, size, &aux, msg);
    msg[size] = 0;
    printf("%s: \"%s\"\n", str, msg);
}

int main(int argc, char **argv) {
    printf("Beginning to test EXT_TRANSFORM_FEEDBACK\n");

    SDL_Init(SDL_INIT_EVERYTHING);
    SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER,1);
    SDL_SetVideoMode(400,300,32,SDL_HWSURFACE|SDL_OPENGL);

    GLuint shid, bid, tmp;
    GLint loc;

    printf("Initialization complete (current error: %d)\n\n",glGetError());

    printf("Loading shader\n");
    shid = glCreateProgramObjectARB();

    tmp = glCreateShaderObjectARB(GL_VERTEX_SHADER_ARB);
    glShaderSourceARB(tmp, 1, (const GLcharARB**)&sourceVert, NULL);
    glCompileShaderARB(tmp);
    checkShader(tmp, GL_OBJECT_COMPILE_STATUS_ARB, "Compile vertex");
    glAttachObjectARB(shid,tmp);

    glLinkProgramARB(shid);
    checkShader(shid, GL_OBJECT_LINK_STATUS_ARB, "Link result");
    printf("Shader loaded (current error: %d)\n\n", glGetError());

    printf("Trying to get location of \"gl_Position\"\n");
    glUseProgramObjectARB(shid);
    loc = glGetVaryingLocationNV(shid,"gl_Position");
    printf("Got location %d (current error: %d)\n\n",loc,glGetError());

    //const char *vars[] = {"out_pos"};
    //glTransformFeedbackVaryingsEXT(shid, 1, vars, GL_SEPARATE_ATTRIBS_EXT); //for GLew?
    const GLint locations[] = {loc};
    glTransformFeedbackVaryingsEXT(shid, 1, locations, GL_SEPARATE_ATTRIBS_EXT); //for GLee?

    printf("Preparing buffer\n");
    glGenBuffersARB(1, &bid);
    glBindBufferARB(GL_ARRAY_BUFFER, bid);
    const float init[] = {0.1f,0.2f,0.3f,0.4f};
    glBufferDataARB(GL_ARRAY_BUFFER, 4*sizeof(float)*1, NULL, GL_STREAM_DRAW);
    printf("Buffer prepared (current error: %d)\n",glGetError());

    glBindBufferBaseEXT(GL_TRANSFORM_FEEDBACK_BUFFER_EXT, 0, bid);
    printf("Feedback assigned (current error: %d)\n\n",glGetError());

    printf("Beginning drawing\n");
    glUseProgramObjectARB(shid);
    glBeginTransformFeedbackEXT(GL_POINTS);
    glEnable(GL_RASTERIZER_DISCARD_EXT);

    glBegin(GL_POINTS);
    printf("In data: ");
    for(int i=0; i<4; ++i) {
        printf("%.1f ", init[i]);
    }
    printf("\n");
    glVertex4fv(init);
    glEnd();

    glDisable(GL_RASTERIZER_DISCARD_EXT);
    glEndTransformFeedbackEXT();
    printf("Drawing completed (current error: %d)\n\n", glGetError());

    printf("Reading (hopefully transformed) data\n");
    float *const data = (float *)glMapBuffer(GL_ARRAY_BUFFER, GL_READ_ONLY);
    printf("Out data: ");
    for(int i=0; i<4; ++i) {
        printf("%.1f ", data[i]);
    }
    printf("\n");
    glUnmapBuffer(GL_ARRAY_BUFFER);
    printf("Readback complete (current error: %d)",glGetError());

    getchar();
    return 0;
}