src/geometry/WallSceneNode.cxx

/* bzflag
 * Copyright (c) 1993-2021 Tim Riker
 *
 * This package is free software;  you can redistribute it and/or
 * modify it under the terms of the license found in the file
 * named COPYING that should have accompanied this file.
 *
 * THIS PACKAGE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

// interface headers
#include "WallSceneNode.h"
#include "PolyWallSceneNode.h"

// system headers
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>

// common implementation headers
#include "StateDatabase.h"
#include "BZDBCache.h"

// local implementation headers
#include "ViewFrustum.h"

// FIXME (SceneRenderer.cxx is in src/bzflag)
#include "SceneRenderer.h"

WallSceneNode::WallSceneNode() : numLODs(0),
    elementAreas(NULL),
    style(0)
{
    dynamicColor = NULL;
    color[3] = 1.0f;
    modulateColor[3] = 1.0f;
    lightedColor[3] = 1.0f;
    lightedModulateColor[3] = 1.0f;
    color[3] = 1.0f;
    color[3] = 1.0f;
    color[3] = 1.0f;
    setColor(1.0f, 1.0f, 1.0f);
    setModulateColor(1.0f, 1.0f, 1.0f);
    setLightedColor(1.0f, 1.0f, 1.0f);
    setLightedModulateColor(1.0f, 1.0f, 1.0f);
    useColorTexture = false;
    noCulling = false;
    noSorting = false;
    isBlended = false;
    wantBlending = false;
    wantSphereMap = false;
    alphaThreshold = 0.0f;
    return;
}

WallSceneNode::~WallSceneNode()
{
    // free element area table
    delete[] elementAreas;
}

const GLfloat* WallSceneNode::getPlane() const
{
    return plane;
}

void            WallSceneNode::setNumLODs(int num, float* areas)
{
    numLODs = num;
    elementAreas = areas;
}

void            WallSceneNode::setPlane(const GLfloat _plane[4])
{
    // get normalization factor
    const float n = 1.0f / sqrtf((_plane[0] * _plane[0]) +
                                 (_plane[1] * _plane[1]) +
                                 (_plane[2] * _plane[2]));

    // store normalized plane equation
    plane[0] = n * _plane[0];
    plane[1] = n * _plane[1];
    plane[2] = n * _plane[2];
    plane[3] = n * _plane[3];
}

bool            WallSceneNode::cull(const ViewFrustum& frustum) const
{
    // cull if eye is behind (or on) plane
    const GLfloat* eye = frustum.getEye();
    const float eyedot = (eye[0] * plane[0]) +
                         (eye[1] * plane[1]) +
                         (eye[2] * plane[2]) + plane[3];
    if (eyedot <= 0.0f)
        return true;

    // if the Visibility culler tells us that we're
    // fully visible, then skip the rest of these tests
    if (octreeState == OctreeVisible)
        return false;

    // get signed distance of wall center to each frustum side.
    // if more than radius outside then cull
    const int planeCount = frustum.getPlaneCount();
    int i;
    float d[6], d2[6];
    const GLfloat* mySphere = getSphere();
    bool inside = true;
    for (i = 0; i < planeCount; i++)
    {
        const GLfloat* norm = frustum.getSide(i);
        d[i] = (mySphere[0] * norm[0]) +
               (mySphere[1] * norm[1]) +
               (mySphere[2] * norm[2]) + norm[3];
        if (d[i] < 0.0f)
        {
            d2[i] = d[i] * d[i];
            if (d2[i] > mySphere[3])
                return true;
            inside = false;
        }
    }

    // see if center of wall is inside each frustum side
    if (inside)
        return false;

    // most complicated test:  for sides sphere is behind, see if
    // center is beyond radius times the sine of the angle between
    // the normals, or equivalently:
    //    distance^2 > radius^2 * (1 - cos^2)
    // if so the wall is outside the view frustum
    for (i = 0; i < planeCount; i++)
    {
        if (d[i] >= 0.0f)
            continue;
        const GLfloat* norm = frustum.getSide(i);
        const GLfloat c = norm[0]*plane[0] + norm[1]*plane[1] + norm[2]*plane[2];
        if (d2[i] > mySphere[3] * (1.0f - c*c))
            return true;
    }

    // probably visible
    return false;
}

int         WallSceneNode::pickLevelOfDetail(
    const SceneRenderer& renderer) const
{
    if (!BZDBCache::tesselation)
        return 0;

    int bestLOD = 0;

    const GLfloat* mySphere = getSphere();
    const int numLights = renderer.getNumLights();
    for (int i = 0; i < numLights; i++)
    {
        const GLfloat* pos = renderer.getLight(i).getPosition();

        // get signed distance from plane
        GLfloat pd = pos[0] * plane[0] + pos[1] * plane[1] +
                     pos[2] * plane[2] + plane[3];

        // ignore if behind wall
        if (pd < 0.0f) continue;

        // get squared distance from center of wall
        GLfloat ld = (pos[0] - mySphere[0]) * (pos[0] - mySphere[0]) +
                     (pos[1] - mySphere[1]) * (pos[1] - mySphere[1]) +
                     (pos[2] - mySphere[2]) * (pos[2] - mySphere[2]);

        // pick representative distance
        GLfloat d = (ld > 1.5f * mySphere[3]) ? ld : pd * pd;

        // choose lod based on distance and element areas;
        int j;
        for (j = 0; j < numLODs - 1; j++)
            if (elementAreas[j] < d)
                break;

        // use new lod if more detailed
        if (j > bestLOD) bestLOD = j;
    }

    // FIXME -- if transient texture warper is active then possibly
    // bump up LOD if view point is close to wall.

    // limit lod to maximum allowed
    if (bestLOD > BZDBCache::maxLOD) bestLOD = (int)BZDBCache::maxLOD;

    // return highest level required -- note that we don't care about
    // the view point because, being flat, the wall would always
    // choose the lowest LOD for any view.
    return bestLOD;
}

GLfloat         WallSceneNode::getDistance(const GLfloat* eye) const
{
    const GLfloat d = plane[0] * eye[0] + plane[1] * eye[1] +
                      plane[2] * eye[2] + plane[3];
    return d * d;
}

void            WallSceneNode::setColor(
    GLfloat r, GLfloat g, GLfloat b, GLfloat a)
{
    color[0] = r;
    color[1] = g;
    color[2] = b;
    color[3] = a;
}

void            WallSceneNode::setDynamicColor(const GLfloat* rgba)
{
    dynamicColor = rgba;
    return;
}

void            WallSceneNode::setBlending(bool blend)
{
    wantBlending = blend;
    return;
}

void            WallSceneNode::setSphereMap(bool sphereMapping)
{
    wantSphereMap = sphereMapping;
    return;
}

void            WallSceneNode::setColor(const GLfloat* rgba)
{
    color[0] = rgba[0];
    color[1] = rgba[1];
    color[2] = rgba[2];
    color[3] = rgba[3];
}

void            WallSceneNode::setModulateColor(
    GLfloat r, GLfloat g, GLfloat b, GLfloat a)
{
    modulateColor[0] = r;
    modulateColor[1] = g;
    modulateColor[2] = b;
    modulateColor[3] = a;
}

void            WallSceneNode::setModulateColor(const GLfloat* rgba)
{
    modulateColor[0] = rgba[0];
    modulateColor[1] = rgba[1];
    modulateColor[2] = rgba[2];
    modulateColor[3] = rgba[3];
}

void            WallSceneNode::setLightedColor(
    GLfloat r, GLfloat g, GLfloat b, GLfloat a)
{
    lightedColor[0] = r;
    lightedColor[1] = g;
    lightedColor[2] = b;
    lightedColor[3] = a;
}

void            WallSceneNode::setLightedColor(const GLfloat* rgba)
{
    lightedColor[0] = rgba[0];
    lightedColor[1] = rgba[1];
    lightedColor[2] = rgba[2];
    lightedColor[3] = rgba[3];
}

void            WallSceneNode::setLightedModulateColor(
    GLfloat r, GLfloat g, GLfloat b, GLfloat a)
{
    lightedModulateColor[0] = r;
    lightedModulateColor[1] = g;
    lightedModulateColor[2] = b;
    lightedModulateColor[3] = a;
}

void            WallSceneNode::setLightedModulateColor(
    const GLfloat* rgba)
{
    lightedModulateColor[0] = rgba[0];
    lightedModulateColor[1] = rgba[1];
    lightedModulateColor[2] = rgba[2];
    lightedModulateColor[3] = rgba[3];
}

void            WallSceneNode::setAlphaThreshold(float thresh)
{
    alphaThreshold = thresh;
}

void            WallSceneNode::setNoCulling(bool value)
{
    noCulling = value;
}

void            WallSceneNode::setNoSorting(bool value)
{
    noSorting = value;
}

void            WallSceneNode::setMaterial(const OpenGLMaterial& mat)
{
    OpenGLGStateBuilder builder(gstate);
    builder.setMaterial(mat);
    gstate = builder.getState();
}

void            WallSceneNode::setTexture(const int tex)
{
    OpenGLGStateBuilder builder(gstate);
    builder.setTexture(tex);
    gstate = builder.getState();
}

void            WallSceneNode::setTextureMatrix(const GLfloat* texmat)
{
    OpenGLGStateBuilder builder(gstate);
    builder.setTextureMatrix(texmat);
    gstate = builder.getState();
}

void            WallSceneNode::notifyStyleChange()
{
    float alpha;
    bool lighted = (BZDBCache::lighting && gstate.isLighted());
    OpenGLGStateBuilder builder(gstate);
    style = 0;
    if (lighted)
    {
        style += 1;
        builder.setShading();
    }
    else
        builder.setShading(GL_FLAT);
    if (BZDBCache::texture && gstate.isTextured())
    {
        style += 2;
        builder.enableTexture(true);
        builder.enableTextureMatrix(true);
        alpha = lighted ? lightedModulateColor[3] : modulateColor[3];
    }
    else
    {
        builder.enableTexture(false);
        builder.enableTextureMatrix(false);
        alpha = lighted ? lightedColor[3] : color[3];
    }
    if (BZDB.isTrue("texturereplace"))
        builder.setTextureEnvMode(GL_REPLACE);
    else
        builder.setTextureEnvMode(GL_MODULATE);
    builder.enableMaterial(lighted);
    if (BZDBCache::blend && (wantBlending || (alpha != 1.0f)))
    {
        builder.setBlending(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
        builder.setStipple(1.0f);
    }
    else
    {
        builder.resetBlending();
        builder.setStipple(alpha);
    }
    isBlended = wantBlending || (alpha != 1.0f);
    if (alphaThreshold != 0.0f)
        builder.setAlphaFunc(GL_GEQUAL, alphaThreshold);
    if (noCulling)
        builder.disableCulling();
    if (noSorting)
        builder.setNeedsSorting(false);
    if (wantSphereMap)
        builder.enableSphereMap(true);
    gstate = builder.getState();
}

void            WallSceneNode::copyStyle(WallSceneNode* node)
{
    gstate = node->gstate;
    useColorTexture = node->useColorTexture;
    dynamicColor = node->dynamicColor;
    setColor(node->color);
    setModulateColor(node->modulateColor);
    setLightedColor(node->lightedColor);
    setLightedModulateColor(node->lightedModulateColor);
    isBlended = node->isBlended;
    wantBlending = node->wantBlending;
    wantSphereMap = node->wantSphereMap;
}

void            WallSceneNode::setColor()
{
    if (BZDBCache::texture && useColorTexture)
        myColor4f(1,1,1,1);
    else if (dynamicColor != NULL)
        myColor4fv(dynamicColor);
    else
    {
        switch (style)
        {
        case 0:
            myColor4fv(color);
            break;
        case 1:
            myColor4fv(lightedColor);
            break;
        case 2:
            myColor4fv(modulateColor);
            break;
        case 3:
            myColor4fv(lightedModulateColor);
            break;
        }
    }
}

int WallSceneNode::splitWall(const GLfloat* splitPlane,
                             const GLfloat3Array& vertices,
                             const GLfloat2Array& texcoords,
                             SceneNode*& front, SceneNode*& back) // const
{
    int i;
    const int count = vertices.getSize();
    const float fudgeFactor = 0.001f;
    const unsigned char BACK_SIDE = (1 << 0);
    const unsigned char FRONT_SIDE = (1 << 1);

    // arrays for tracking each vertex's side
    // and distance from the splitting plane
    // (assuming stack allocation with be faster then heap, might be wrong)
    // wonder how that compares to static vs. stack access speeds
    const int staticSize = 64;
    float* dists;
    unsigned char* array;
    float staticDists[staticSize];
    unsigned char staticArray[staticSize];
    if (count > staticSize)
    {
        array = new unsigned char[count];
        dists = new float[count];
    }
    else
    {
        array = staticArray;
        dists = staticDists;
    }

    // determine on which side of the plane each point lies
    int bothCount = 0;
    int backCount = 0;
    int frontCount = 0;
    for (i = 0; i < count; i++)
    {
        const GLfloat d = (vertices[i][0] * splitPlane[0]) +
                          (vertices[i][1] * splitPlane[1]) +
                          (vertices[i][2] * splitPlane[2]) + splitPlane[3];
        if (d < -fudgeFactor)
        {
            array[i] = BACK_SIDE;
            backCount++;
        }
        else if (d > fudgeFactor)
        {
            array[i] = FRONT_SIDE;
            frontCount++;
        }
        else
        {
            array[i] = (BACK_SIDE | FRONT_SIDE);
            bothCount++;
            backCount++;
            frontCount++;
        }
        dists[i] = d; // save for later
    }

    // see if we need to split
    if ((frontCount == 0) || (frontCount == bothCount))
    {
        if (count > staticSize)
        {
            delete[] array;
            delete[] dists;
        }
        return -1; // node is on the back side
    }

    if ((backCount == 0) || (backCount == bothCount))
    {
        if (count > staticSize)
        {
            delete[] array;
            delete[] dists;
        }
        return +1; // node is on the front side
    }

    // get the first old front and back points
    int firstFront = -1, firstBack = -1;

    for (i = 0; i < count; i++)
    {

        const int next = (i + 1) % count; // the next index

        if (array[next] & FRONT_SIDE)
        {
            if (!(array[i] & FRONT_SIDE))
                firstFront = next;
        }
        if (array[next] & BACK_SIDE)
        {
            if (!(array[i] & BACK_SIDE))
                firstBack = next;
        }
    }

    // get the last old front and back points
    int lastFront = (firstFront + frontCount - 1) % count;
    int lastBack = (firstBack + backCount - 1) % count;

    // add in extra counts for the splitting vertices
    if (firstFront != lastBack)
    {
        frontCount++;
        backCount++;
    }
    if (firstBack != lastFront)
    {
        frontCount++;
        backCount++;
    }

    // make space for new polygons
    GLfloat3Array vertexFront(frontCount);
    GLfloat2Array uvFront(frontCount);
    GLfloat3Array vertexBack(backCount);
    GLfloat2Array uvBack(backCount);

    // fill in the splitting vertices
    int frontIndex = 0;
    int backIndex = 0;
    if (firstFront != lastBack)
    {
        GLfloat splitVertex[3], splitUV[2];
        splitEdge(dists[firstFront], dists[lastBack],
                  vertices[firstFront], vertices[lastBack],
                  texcoords[firstFront], texcoords[lastBack],
                  splitVertex, splitUV);
        memcpy(vertexFront[0], splitVertex, sizeof(GLfloat[3]));
        memcpy(uvFront[0], splitUV, sizeof(GLfloat[2]));
        frontIndex++; // bump up the head
        const int last = backCount - 1;
        memcpy(vertexBack[last], splitVertex, sizeof(GLfloat[3]));
        memcpy(uvBack[last], splitUV, sizeof(GLfloat[2]));
    }
    if (firstBack != lastFront)
    {
        GLfloat splitVertex[3], splitUV[2];
        splitEdge(dists[firstBack], dists[lastFront],
                  vertices[firstBack], vertices[lastFront],
                  texcoords[firstBack], texcoords[lastFront],
                  splitVertex, splitUV);
        memcpy(vertexBack[0], splitVertex, sizeof(GLfloat[3]));
        memcpy(uvBack[0], splitUV, sizeof(GLfloat[2]));
        backIndex++; // bump up the head
        const int last = frontCount - 1;
        memcpy(vertexFront[last], splitVertex, sizeof(GLfloat[3]));
        memcpy(uvFront[last], splitUV, sizeof(GLfloat[2]));
    }

    // fill in the old front side vertices
    const int endFront = (lastFront + 1) % count;
    for (i = firstFront; i != endFront; i = (i + 1) % count)
    {
        memcpy(vertexFront[frontIndex], vertices[i], sizeof(GLfloat[3]));
        memcpy(uvFront[frontIndex], texcoords[i], sizeof(GLfloat[2]));
        frontIndex++;
    }

    // fill in the old back side vertices
    const int endBack = (lastBack + 1) % count;
    for (i = firstBack; i != endBack; i = (i + 1) % count)
    {
        memcpy(vertexBack[backIndex], vertices[i], sizeof(GLfloat[3]));
        memcpy(uvBack[backIndex], texcoords[i], sizeof(GLfloat[2]));
        backIndex++;
    }

    // make new nodes
    front = new PolyWallSceneNode(vertexFront, uvFront);
    back = new PolyWallSceneNode(vertexBack, uvBack);

    // free the arrays, if required
    if (count > staticSize)
    {
        delete[] array;
        delete[] dists;
    }

    return 0; // generated new front and back nodes
}


void WallSceneNode::splitEdge(float d1, float d2,
                              const GLfloat* p1, const GLfloat* p2,
                              const GLfloat* uv1, const GLfloat* uv2,
                              GLfloat* p, GLfloat* uv) // const
{
    // compute fraction along edge where split occurs
    float t1 = (d2 - d1);
    if (t1 != 0.0f)   // shouldn't happen
        t1 = -(d1 / t1);

    // compute vertex
    p[0] = p1[0] + (t1 * (p2[0] - p1[0]));
    p[1] = p1[1] + (t1 * (p2[1] - p1[1]));
    p[2] = p1[2] + (t1 * (p2[2] - p1[2]));

    // compute texture coordinate
    uv[0] = uv1[0] + (t1 * (uv2[0] - uv1[0]));
    uv[1] = uv1[1] + (t1 * (uv2[1] - uv1[1]));
}


bool WallSceneNode::inAxisBox (const Extents& UNUSED(exts)) const
{
    // this should never happen, only the TriWallSceneNode
    // and QuadWallSceneNode version of this function will
    // be called
    printf ("WallSceneNode::inAxisBox() was called!\n");
    exit (1);
    return false;
}

// Local Variables: ***
// mode: C++ ***
// tab-width: 4 ***
// c-basic-offset: 4 ***
// indent-tabs-mode: nil ***
// End: ***
// ex: shiftwidth=4 tabstop=4