/*

 *  pbuffer.c

 *  GLCarbon1ContextPbuffer

 *

 *  Created by Geoff Stahl on Fri Feb 20 2004.

 *  Copyright (c) 2004 Apple. All rights reserved.

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 */

#include <OpenGL/gl.h>

#include <OpenGL/glext.h>

#include "pbuffer.h"

#include "SurfaceGeometry.h"

#include "main.h"

void initialConditionsPbuffer (pRecPbuffer pPbufferInfo)

{

    BlockZero (pPbufferInfo, sizeof (recPbuffer));

    resetCamera (&pPbufferInfo->camera);

    pPbufferInfo->camera.viewPos.z = -16.0;

    pPbufferInfo->camera.viewWidth = (float) kPbufferWidth;

    pPbufferInfo->camera.viewHeight = (float) kPbufferHeight;

    pPbufferInfo->shapeSize = 11.0f; // max radius of of objects in window

    pPbufferInfo->fVel[0] = 0.3; pPbufferInfo->fVel[1] = 0.1; pPbufferInfo->fVel[2] = 0.2; 

    pPbufferInfo->fAccel[0] = 0.003; pPbufferInfo->fAccel[1] = -0.005; pPbufferInfo->fAccel[2] = 0.004;

    pPbufferInfo->animate = kAnimateState;

    pPbufferInfo->polygons = 1;

    pPbufferInfo->lighting = 1;

    pPbufferInfo->surface = kTranguloidTrefoil;

    pPbufferInfo->subdivisions = 64;

    pPbufferInfo->colorScheme = 4;

    pPbufferInfo->xyRatio = 3;

    // set up pbuffer update timer

    pPbufferInfo->time = UpTime ();

    pPbufferInfo->currentVS = -1; // no screen

}

// ---------------------------------

OSStatus buildPbuffer (pRecPbuffer pPbufferInfo)

{

    OSStatus err = noErr;

    // no pixel format required since using windows context

#pragma mark *** create pbuffer ***

#if kUseNonPowerOf2

        if (!aglCreatePBuffer (kPbufferWidth, kPbufferHeight, GL_TEXTURE_RECTANGLE_EXT, GL_RGBA, kPbufferMaxLevels, &(pPbufferInfo->aglPbuffer)))

#else

    if (!aglCreatePBuffer (kPbufferWidth, kPbufferHeight, GL_TEXTURE_2D, GL_RGBA, kPbufferMaxLevels, &(pPbufferInfo->aglPbuffer)))

#endif          

        err = aglReportError ();

    // do attach drawable to correct virtual screen and context setting at draw time

    // this means we will not set up the GL state until that time

    return err;

}

// ---------------------------------

void updatePbuffer (AGLContext targetContext, pRecPbuffer pPbufferInfo)

{

    float deltaTime = 0.0f;

    if (targetContext) { // if we have a target context to use when drawing...

        // make pbuffer current (as we are drawing into it)

        if (!aglSetCurrentContext (pPbufferInfo->aglContext)) {

            aglReportError ();

            return;

        }

        // update and draw pbuffer content for current target context (this ensures we are actually drawing on the same renderer)

        GLint vs = aglGetVirtualScreen (targetContext);

        aglReportError ();

        if (pPbufferInfo->currentVS != vs) {

            pPbufferInfo->dirty = true;

            pPbufferInfo->currentVS = vs;

            // since we have to set pbuffer as drawable every time we draw, do this in the drawing code below

        }

        // find time delta if we are animating (60 fps update here as an example)

        // this scheme does not account for stopping the clock while not animating (exercise left for developer if desired)

        if (pPbufferInfo->animate) {

            AbsoluteTime currTime = UpTime ();

            deltaTime = (float) AbsoluteDeltaToDuration (currTime, pPbufferInfo->time);

            if (0 > deltaTime)  // if negative microseconds

                deltaTime /= -1000000.0;

            else                // else milliseconds

                deltaTime /= 1000.0;

            if (deltaTime > 0.0167) { // update contents at 60 fps

                pPbufferInfo->time = currTime;  // reset for next time interval

            pPbufferInfo->dirty = true;

            }

        }

        // so, if after all that we actually need to be drawn then draw pbuffer content

        if (pPbufferInfo->dirty) {

            // must set single context's drawable to pbuffer to draw

#pragma mark *** set pbuffer as drawable ***

            if (!aglSetPBuffer (pPbufferInfo->aglContext, pPbufferInfo->aglPbuffer, 0, 0, pPbufferInfo->currentVS)) { //equivalent of SetDrawable

                pPbufferInfo->currentVS = -1; // error

                aglReportError ();

                return;

            }

            if (pPbufferInfo->animate)

                updateRotation (deltaTime, pPbufferInfo->fRot, pPbufferInfo->fVel, pPbufferInfo->fAccel, pPbufferInfo->objectRotation);

            // reset GL for pbuffer drawing

            glViewport (0, 0, pPbufferInfo->camera.viewWidth, pPbufferInfo->camera.viewHeight); // set viewport to pbuffer size

            updateProjection (1.0f, 1.0f, pPbufferInfo->camera.viewPos.z,                // do not compensate for no square view (that is taken care with texture coord and mapping)

                              pPbufferInfo->camera.aperture, pPbufferInfo->shapeSize);

            updateModelView (pPbufferInfo->aglContext, &pPbufferInfo->camera, 

                             pPbufferInfo->fRot, pPbufferInfo->objectRotation, NULL);

            // draw

#pragma mark *** draw to pbuffer ***

            glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

            if (pPbufferInfo->polygons) {

                if (pPbufferInfo->lighting)

                    glEnable(GL_LIGHTING);

                else 

                    glDisable(GL_LIGHTING);

                glCallList (pPbufferInfo->polyList);

                glDisable(GL_LIGHTING);

            } else if (pPbufferInfo->lines) {

                glDisable(GL_LIGHTING);

                glCallList (pPbufferInfo->lineList);

            } else if (pPbufferInfo->points) {

                glDisable(GL_LIGHTING);

                glCallList (pPbufferInfo->pointList);

            }

            aglSwapBuffers (pPbufferInfo->aglContext); // context double buffered sp we must flip (unless we texture from back buffer, see aglTexImagePBuffer)

        }

        aglSetCurrentContext (NULL); // ensure we are not still drawing to Pbuffer

        pPbufferInfo->dirty = false; // we are no longer dirty

    }

}

// ---------------------------------

void dirtyPbuffer (pRecPbuffer pPbufferInfo) 

{

    pPbufferInfo->dirty = true;

}

// ---------------------------------

void bindPbuffer (AGLContext targetContext, pRecPbuffer pPbufferInfo)

{ // pbuffers require non-default texture name

#if 0

// test code: forces a texture generation on every bindPbuffer

    if (0 != pPbufferInfo->texName)

        glDeleteTextures (1, & pPbufferInfo->texName);

    pPbufferInfo->texName = 0;

#endif

#pragma mark *** bind pbuffer as texture ***

    if (0 == pPbufferInfo->texName) { // if no texture name create one and texture from the pbuffer

        glGenTextures (1, &pPbufferInfo->texName);

#if kUseNonPowerOf2

        glBindTexture (GL_TEXTURE_RECTANGLE_EXT, pPbufferInfo->texName);

        glTexParameterf (GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

#else

        glBindTexture (GL_TEXTURE_2D, pPbufferInfo->texName);

        glTexParameterf (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

#endif

        aglTexImagePBuffer (targetContext, pPbufferInfo->aglPbuffer, GL_FRONT);

    } else { // else just bind 

        // (without mipmaps pbuffer changes will be picked up, mipmaps require aglTexImagePBuffer for updates)

#if kUseNonPowerOf2

        glBindTexture (GL_TEXTURE_RECTANGLE_EXT, pPbufferInfo->texName);

#else

        glBindTexture (GL_TEXTURE_2D, pPbufferInfo->texName);

#endif

        glReportError ();

    }

}

// ---------------------------------

OSStatus disposePbuffer(pRecPbuffer pPbufferInfo)

{

    OSStatus err = noErr;

    if (pPbufferInfo->texName)

        glDeleteTextures (1, &pPbufferInfo->texName);

        aglSetCurrentContext (NULL);

    if (pPbufferInfo->aglPbuffer) {

#pragma mark *** dispose pbuffer ***

        aglDestroyPBuffer (pPbufferInfo->aglPbuffer);

        pPbufferInfo->aglPbuffer = NULL;

    }

    // no context (using window's)

    // no pixel format (using window's)

    return err;

}