#include "gl.h"
#include "glu.h"
#include "glkos.h"

/* A general OpenGL initialization function.  Sets all of the initial parameters. */
void InitGL(int Width, int Height)	        // We call this right after our OpenGL window is created.
{
    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);		// This Will Clear The Background Color To Black
    glClearDepth(1.0);				// Enables Clearing Of The Depth Buffer
    glDepthFunc(GL_LEQUAL);				// The Type Of Depth Test To Do
    glEnable(GL_DEPTH_TEST);			// Enables Depth Testing
    glShadeModel(GL_SMOOTH);			// Enables Smooth Color Shading

    glEnableClientState(GL_VERTEX_ARRAY); // Enable vertex arrays

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();				// Reset The Projection Matrix

    gluPerspective(45.0f,(GLfloat)Width/(GLfloat)Height,0.1f,100.0f);	// Calculate The Aspect Ratio Of The Window

    glMatrixMode(GL_MODELVIEW);
}

/* The function called when our window is resized (which shouldn't happen, because we're fullscreen) */
void ReSizeGLScene(int Width, int Height)
{
    if (Height == 0)				// Prevent A Divide By Zero If The Window Is Too Small
        Height = 1;

    glViewport(0, 0, Width, Height);		// Reset The Current Viewport And Perspective Transformation

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();

    gluPerspective(45.0f,(GLfloat)Width/(GLfloat)Height,0.1f,100.0f);
    glMatrixMode(GL_MODELVIEW);
}


/* The main drawing function. */
void DrawGLScene()
{

    const GLfloat triangle [] = {
        0.0f, 1.0f, 0.0f,
        1.0f, -1.0f, 0.0f,
        -1.0f, -1.0f, 0.0f
    };

    const GLfloat square [] = {
        -1.0f, 1.0f, 0.0f,
        1.0f, 1.0f, 0.0f,
        1.0f, -1.0f, 0.0f,
        -1.0f, -1.0f, 0.0f
    };

    const GLuint triangleIdx [] = {
        0, 1, 2
    };

    const GLuint squareIdx [] = {
        0, 1, 2, 3
    };

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);		// Clear The Screen And The Depth Buffer
    glLoadIdentity();				// Reset The View

    glTranslatef(-1.5f,0.0f,-6.0f);		// Move Left 1.5 Units And Into The Screen 6.0

    glVertexPointer(3, GL_FLOAT, 0, triangle);
    glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_INT, triangleIdx);

    glTranslatef(3.0f,0.0f,0.0f);		        // Move Right 3 Units

    glVertexPointer(3, GL_FLOAT, 0, square);
    glDrawElements(GL_QUADS, 4, GL_UNSIGNED_INT, squareIdx);

    // swap buffers to display, since we're double buffered.
    glKosSwapBuffers();
}

int main(int argc, char **argv)
{
    glKosInit();

    InitGL(640, 480);
    ReSizeGLScene(640, 480);

    while(1) {
        DrawGLScene();
    }

    return 0;
}