cp_overlay.cpp

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/*
Copyright (C) 1997-2001 Id Software, Inc.

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

*/

#include "../../cl_shared.h"
#include "cp_campaign.h"
#include "cp_overlay.h"

static const int MAX_ALPHA_VALUE = 200;
static const int INITIAL_ALPHA_VALUE = 60;

static inline byte* CP_XVIGetAlpha (int x, int y)
{
    return &cgi->r_xviAlpha[y * XVI_WIDTH + x];
}

static inline byte* CP_RadarGet (int x, int y, bool source)
{
    if (source)
        return &cgi->r_radarSourcePic[y * RADAR_WIDTH + x];
    return &cgi->r_radarPic[y * RADAR_WIDTH + x];
}

static inline void CP_UploadXVI (void)
{
    cgi->R_UploadAlpha("***r_xvitexture***", cgi->r_xviAlpha);
}

void CP_GetXVIMapDimensions (int* width, int* height)
{
    *width = XVI_WIDTH;
    *height = XVI_HEIGHT;
}

void CP_SetXVILevel (int x, int y, int value)
{
    assert(x >= 0);
    assert(x < XVI_WIDTH);
    assert(y >= 0);
    assert(y < XVI_HEIGHT);

    if (!value)
        *CP_XVIGetAlpha(x, y) = 0;
    else
        *CP_XVIGetAlpha(x, y) = std::min(MAX_ALPHA_VALUE, value + INITIAL_ALPHA_VALUE);
}

int CP_GetXVILevel (int x, int y)
{
    assert(x >= 0);
    assert(x < XVI_WIDTH);
    assert(y >= 0);
    assert(y < XVI_HEIGHT);

    return std::max(0, *CP_XVIGetAlpha(x, y) - INITIAL_ALPHA_VALUE);
}

static void CP_SetMinMaxOverlayRows (const vec2_t pos, float radius, const int height, int* yMin, int* yMax)
{
    const float radarHeightPerDegree = height / 180.0f;

    if (pos[1] + radius > 90) {
        *yMin = 0;
        *yMax = round((90 - pos[1] + radius) * radarHeightPerDegree);
    } else if (pos[1] - radius < -90) {
        *yMin = ceil((90 - pos[1] - radius) * radarHeightPerDegree);
        *yMax = height;
    } else {
        *yMin = ceil((90 - pos[1] - radius) * radarHeightPerDegree);
        *yMax = round((90 - pos[1] + radius) * radarHeightPerDegree);
    }

    /* a few assert to avoid buffer overflow */
    assert(*yMin >= 0);
    assert(*yMin <= *yMax);
    assert(*yMax <= height);            /* the loop will stop just BEFORE yMax, so use <= rather than < */
}

static inline float CP_GetCircleDeltaLongitude (const vec2_t centerPos, float radius, const float yLat)
{
    const float angle = (cos(radius * torad) - sin(centerPos[1] * torad) * sin(yLat)) / (cos(centerPos[1] * torad) * cos(yLat));
    return fabs(angle) > 1.0f ? 180.0f : todeg * acos(angle);
}

static void CP_DrawXVIOverlayPixel (int xMin, int xMax, const vec2_t centerPos, int y, const float yLat, int xviLevel, float radius)
{
    int x;
    vec2_t currentPos;

    currentPos[1] = yLat;

    for (x = xMin; x < xMax; x++) {
        const int previousLevel = CP_GetXVILevel(x, y);
        float distance;
        int newLevel;

        currentPos[0] = 180.0f - 360.0f * x / ((float) XVI_WIDTH);
        distance = GetDistanceOnGlobe(centerPos, currentPos);
        newLevel = ceil((xviLevel * (radius - distance)) / radius);
        if (newLevel > previousLevel)
            CP_SetXVILevel(x, y, xviLevel);
    }
}

static void CP_DrawXVIOverlayRow (float latMin, float latMax, const vec2_t center, int y, float yLat, int xviLevel, float radius)
{
    const float xviWidthPerDegree = XVI_WIDTH / 360.0f;

    assert(latMax - latMin <= 360 + EQUAL_EPSILON);

    /* if the disc we draw cross the left or right edge of the picture, we need to
     * draw 2 part of circle on each side of the overlay */
    if (latMin < -180.0f) {
        int xMin = 0;
        int xMax = ceil((latMax + 180.0f) * xviWidthPerDegree);
        CP_DrawXVIOverlayPixel(xMin, xMax, center, y, yLat, xviLevel, radius);
        xMin = floor((latMin + 540.0f) * xviWidthPerDegree);
        xMax = RADAR_WIDTH;
        CP_DrawXVIOverlayPixel(xMin, xMax, center, y, yLat, xviLevel, radius);
    } else if (latMax > 180.0f) {
        int xMin = 0;
        int xMax = ceil((latMax - 180.0f) * xviWidthPerDegree);
        CP_DrawXVIOverlayPixel(xMin, xMax, center, y, yLat, xviLevel, radius);
        xMin = floor((latMin + 180.0f) * xviWidthPerDegree);
        xMax = RADAR_WIDTH;
        CP_DrawXVIOverlayPixel(xMin, xMax, center, y, yLat, xviLevel, radius);
    } else {
        const int xMin = floor((latMin + 180.0f) * xviWidthPerDegree);
        const int xMax = ceil((latMax + 180.0f) * xviWidthPerDegree);
        CP_DrawXVIOverlayPixel(xMin, xMax, center, y, yLat, xviLevel, radius);
    }
}

static void CP_IncreaseXVILevel (const vec2_t pos, int xCenter, int yCenter, float factor)
{
    int xviLevel;                               
    int y;                                      
    int yMax, yMin;                             
    float radius;                               
    /* Get xvi Level infection at pos */
    xviLevel = CP_GetXVILevel(xCenter, yCenter);
    /* Calculate radius of new spreading */
    if (xviLevel < MAX_ALPHA_VALUE - INITIAL_ALPHA_VALUE)
        xviLevel++;
    radius = sqrt(factor * xviLevel);

    /* Set minimum and maximum rows value we'll have to change */
    CP_SetMinMaxOverlayRows(pos, radius, XVI_HEIGHT, &yMin, &yMax);

    for (y = yMin; y < yMax; y++) {
        const float yLat = 90.0f - 180.0f * y / ((float) XVI_HEIGHT);
        const float deltaLong = CP_GetCircleDeltaLongitude(pos, radius, torad * yLat);

        CP_DrawXVIOverlayRow(-pos[0] - deltaLong, -pos[0] + deltaLong, pos, y, yLat, xviLevel, radius);
    }

    CP_UploadXVI();
}

void CP_DecreaseXVILevelEverywhere (void)
{
    for (int y = 0; y < XVI_HEIGHT; y++) {
        for (int x = 0; x < XVI_WIDTH; x++) {
            const int xviLevel = CP_GetXVILevel(x, y);
            if (xviLevel > 0)
                CP_SetXVILevel(x, y, xviLevel - 1);
        }
    }

    CP_UploadXVI();
}

void CP_ChangeXVILevel (const vec2_t pos, float factor)
{
    const int xCenter = round((180 - pos[0]) * XVI_WIDTH / 360.0f);
    const int yCenter = round((90 - pos[1]) * XVI_HEIGHT / 180.0f);

    CP_IncreaseXVILevel(pos, xCenter, yCenter, factor);
}

void CP_InitializeXVIOverlay (void)
{
    /* data Pointer to the data containing values to store in XVI map. Can be nullptr for new games.
     * This is only the alpha channel of the xvi map */
    memset(cgi->r_xviAlpha, 0, XVI_WIDTH * XVI_HEIGHT);
    CP_UploadXVI();
}

/*
 * @brief Radar overlay code description
 * The radar overlay is handled 2 times: bases radar range and aircraft radar range.
 * Bases radar range needs to be updated only when a radar facility is built or destroyed.
 * The base radar overlay is stored in r_radarSourcePic.
 * Aircraft radar overlay needs to be updated every time an aircraft moves, because the position of the radar moves.
 * this overlay is created by duplicating r_radarSourcePic, and then adding any aircraft radar coverage. It is stored in r_radarTexture
 * @sa RADAR_UpdateWholeRadarOverlay
 */

void CP_InitializeRadarOverlay (bool source)
{
    /* Initialize Radar */
    if (source)
        memset(cgi->r_radarSourcePic, INITIAL_ALPHA_VALUE, RADAR_WIDTH * RADAR_HEIGHT);
    else
        memcpy(cgi->r_radarPic, cgi->r_radarSourcePic, RADAR_WIDTH * RADAR_HEIGHT);
}

static void CP_DrawRadarOverlayRow (float latMin, float latMax, int y, byte alpha, bool source)
{
    const float radarWidthPerDegree = RADAR_WIDTH / 360.0f;
    int x;

    assert(latMax - latMin <= 360 + EQUAL_EPSILON);

    /* if the disc we draw cross the left or right edge of the picture, we need to
     * draw 2 part of circle on each side of the overlay */
    if (latMin < -180.0f) {
        int xMin = 0;
        int xMax = ceil((latMax + 180.0f) * radarWidthPerDegree);
        for (x = xMin; x < xMax; x++) {
            byte* dest = CP_RadarGet(x, y, source);
            if (alpha < dest[3])
                dest[3] = alpha;
        }
        xMin = floor((latMin + 540.0f) * radarWidthPerDegree);
        xMax = RADAR_WIDTH;
        for (x = xMin; x < xMax; x++) {
            byte* dest = CP_RadarGet(x, y, source);
            if (alpha < dest[3])
                dest[3] = alpha;
        }
    } else if (latMax > 180.0f) {
        int xMin = 0;
        int xMax = ceil((latMax - 180.0f) * radarWidthPerDegree);
        for (x = xMin; x < xMax; x++) {
            byte* dest = CP_RadarGet(x, y, source);
            if (alpha < dest[3])
                dest[3] = alpha;
        }
        xMin = floor((latMin + 180.0f) * radarWidthPerDegree);
        xMax = RADAR_WIDTH;
        for (x = xMin; x < xMax; x++) {
            byte* dest = CP_RadarGet(x, y, source);
            if (alpha < dest[3])
                dest[3] = alpha;
        }
    } else {
        const int xMin = floor((latMin + 180.0f) * radarWidthPerDegree);
        const int xMax = ceil((latMax + 180.0f) * radarWidthPerDegree);
        for (x = xMin; x < xMax; x++) {
            byte* dest = CP_RadarGet(x, y, source);
            if (alpha < dest[3])
                dest[3] = alpha;
        }
    }
}

void CP_AddRadarCoverage (const vec2_t pos, float innerRadius, float outerRadius, bool source)
{
    const byte innerAlpha = 0;                  
    const byte outerAlpha = 60;                 
    const float radarHeightPerDegree = RADAR_HEIGHT / 180.0f;
    int y;                                      
    int yMax, yMin;                             
    int outeryMax, outeryMin;                   
    assert(outerRadius < 180.0f);
    assert(outerRadius > innerRadius);

    /* Set minimum and maximum rows value we'll have to change */
    CP_SetMinMaxOverlayRows(pos, innerRadius, RADAR_HEIGHT, &yMin, &yMax);
    CP_SetMinMaxOverlayRows(pos, outerRadius, RADAR_HEIGHT, &outeryMin, &outeryMax);

    /* Draw upper part of the radar coverage */
    for (y = outeryMin; y < yMin; y++) {
        /* latitude of current point, in radian */
        const float yLat = torad * (90.0f - y / radarHeightPerDegree);
        float outerDeltaLong = CP_GetCircleDeltaLongitude(pos, outerRadius, yLat);

        /* Only the outer radar coverage is drawn at this latitude */
        CP_DrawRadarOverlayRow(-pos[0] - outerDeltaLong, -pos[0] + outerDeltaLong, y, outerAlpha, source);
    }

    /* Draw middle part of the radar coverage */
    for (y = yMin; y < yMax; y++) {
        /* latitude of current point, in radian */
        const float yLat = torad * (90.0f - y / radarHeightPerDegree);
        const float deltaLong = CP_GetCircleDeltaLongitude(pos, innerRadius, yLat);
        const float outerDeltaLong = CP_GetCircleDeltaLongitude(pos, outerRadius, yLat);

        /* At this latitude, there are 3 parts to draw: left outer radar, inner radar, and right outer radar */
        CP_DrawRadarOverlayRow(-pos[0] - outerDeltaLong, -pos[0] - deltaLong, y, outerAlpha, source);
        CP_DrawRadarOverlayRow(-pos[0] - deltaLong, -pos[0] + deltaLong, y, innerAlpha, source);
        CP_DrawRadarOverlayRow(-pos[0] + deltaLong, -pos[0] + outerDeltaLong, y, outerAlpha, source);
    }

    /* Draw lower part of the radar coverage */
    for (y = yMax; y < outeryMax; y++) {
        /* latitude of current point, in radian */
        const float yLat = torad * (90.0f - y / radarHeightPerDegree);
        const float outerDeltaLong = CP_GetCircleDeltaLongitude(pos, outerRadius, yLat);

        /* Only the outer radar coverage is drawn at this latitude */
        CP_DrawRadarOverlayRow(-pos[0] - outerDeltaLong, -pos[0] + outerDeltaLong, y, outerAlpha, source);
    }
}

void CP_UploadRadarCoverage (void)
{
    cgi->R_SoftenTexture(cgi->r_radarPic, RADAR_WIDTH, RADAR_HEIGHT, 1);
    cgi->R_UploadAlpha("***r_radarTexture***", cgi->r_radarPic);
}