r_geoscape.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 "r_local.h"
#include "r_error.h"
#include "r_sphere.h"
#include "r_geoscape.h"

#include "r_mesh.h"
#include "r_draw.h"

#include "../DateTime.h"

#define MARKER_SIZE 60.0

void R_DrawFlatGeoscape (const vec2_t nodePos, const vec2_t nodeSize, float p, float cx, float cy, float iz, const char* map, bool overlayNation, bool overlayXVI, bool overlayRadar, image_t* r_dayandnightTexture, image_t* r_xviTexture, image_t* r_radarTexture)
{
    image_t* gl;
    float geoscape_texcoords[4 * 2];
    short geoscape_verts[4 * 2];

    /* normalize */
    const float nx = nodePos[0] * viddef.rx;
    const float ny = nodePos[1] * viddef.ry;
    const float nw = nodeSize[0] * viddef.rx;
    const float nh = nodeSize[1] * viddef.ry;

    /* load day image */
    gl = R_FindImage(va("pics/geoscape/%s_day", map), it_wrappic);
    if (gl == r_noTexture)
        Com_Error(ERR_FATAL, "Could not load geoscape day image");

    /* alter the array pointers */
    glVertexPointer(2, GL_SHORT, 0, geoscape_verts);
    R_BindArray(GL_TEXTURE_COORD_ARRAY, GL_FLOAT, geoscape_texcoords);

    geoscape_texcoords[0] = cx - iz;
    geoscape_texcoords[1] = cy - iz;
    geoscape_texcoords[2] = cx + iz;
    geoscape_texcoords[3] = cy - iz;
    geoscape_texcoords[4] = cx + iz;
    geoscape_texcoords[5] = cy + iz;
    geoscape_texcoords[6] = cx - iz;
    geoscape_texcoords[7] = cy + iz;

    geoscape_verts[0] = nx;
    geoscape_verts[1] = ny;
    geoscape_verts[2] = nx + nw;
    geoscape_verts[3] = ny;
    geoscape_verts[4] = nx + nw;
    geoscape_verts[5] = ny + nh;
    geoscape_verts[6] = nx;
    geoscape_verts[7] = ny + nh;

    /* draw day image */
    R_BindTexture(gl->texnum);
    glDrawArrays(GL_TRIANGLE_FAN, 0, 4);

    refdef.batchCount++;

    /* draw night map */
    gl = R_FindImage(va("pics/geoscape/%s_night", map), it_wrappic);
    /* maybe the campaign map doesn't have a night image */
    if (gl != r_noTexture) {
        float geoscape_nighttexcoords[4 * 2];

        R_BindTexture(gl->texnum);
        R_EnableTexture(&texunit_lightmap, true);
        R_SelectTexture(&texunit_lightmap);

        geoscape_nighttexcoords[0] = geoscape_texcoords[0] + p;
        geoscape_nighttexcoords[1] = geoscape_texcoords[1];
        geoscape_nighttexcoords[2] = geoscape_texcoords[2] + p;
        geoscape_nighttexcoords[3] = geoscape_texcoords[3];
        geoscape_nighttexcoords[4] = geoscape_texcoords[4] + p;
        geoscape_nighttexcoords[5] = geoscape_texcoords[5];
        geoscape_nighttexcoords[6] = geoscape_texcoords[6] + p;
        geoscape_nighttexcoords[7] = geoscape_texcoords[7];

        R_BindArray(GL_TEXTURE_COORD_ARRAY, GL_FLOAT, geoscape_nighttexcoords);

        R_BindTexture(r_dayandnightTexture->texnum);

        R_SelectTexture(&texunit_diffuse);
        glDrawArrays(GL_TRIANGLE_FAN, 0, 4);

        refdef.batchCount++;

        R_SelectTexture(&texunit_lightmap);
        R_BindArray(GL_TEXTURE_COORD_ARRAY, GL_FLOAT, geoscape_texcoords);

        R_EnableTexture(&texunit_lightmap, false);
    }

    /* draw nation overlay */
    if (overlayNation) {
        gl = R_FindImage(va("pics/geoscape/%s_nations_overlay", map), it_wrappic);
        if (gl == r_noTexture)
            Com_Error(ERR_FATAL, "Could not load geoscape nation overlay image");

        /* draw day image */
        R_BindTexture(gl->texnum);
        glDrawArrays(GL_TRIANGLE_FAN, 0, 4);

        refdef.batchCount++;
    }

    /* draw XVI image */
    if (overlayXVI) {
        gl = R_FindImage(va("pics/geoscape/%s_xvi_overlay", map), it_wrappic);
        if (gl == r_noTexture)
            Com_Error(ERR_FATAL, "Could not load xvi overlay image");

        R_BindTexture(gl->texnum);

        R_EnableTexture(&texunit_lightmap, true);
        R_BindLightmapTexture(r_xviTexture->texnum);

        glDrawArrays(GL_TRIANGLE_FAN, 0, 4);

        refdef.batchCount++;

        R_EnableTexture(&texunit_lightmap, false);
    }

    /* draw radar image */
    if (overlayRadar) {
        R_BindTexture(r_radarTexture->texnum);
        glDrawArrays(GL_TRIANGLE_FAN, 0, 4);

        refdef.batchCount++;
    }

    /* and restore them */
    R_BindDefaultArray(GL_TEXTURE_COORD_ARRAY);
    R_BindDefaultArray(GL_VERTEX_ARRAY);
}

void R_Draw2DMapMarkers (const vec2_t screenPos, float direction, const char* model, int skin)
{
    modelInfo_t mi;
    vec2_t size;
    vec3_t scale, center, position, angles;
    float zoom = 0.4f;

    OBJZERO(mi);
    VectorCopy(vec3_origin, position);
    VectorCopy(vec3_origin, angles);

    mi.model = R_FindModel(model);
    if (!mi.model) {
        Com_Printf("Could not find model '%s'\n", model);
        return;
    }

    mi.name = model;
    mi.origin = position;
    mi.angles = angles;
    mi.skin = skin;

    size[0] = size[1] = MARKER_SIZE * zoom;
    R_ModelAutoScale(size, &mi, scale, center);
    /* reset the center, as we want to place the models onto the surface of the earth */
    mi.center = nullptr;

    /* go to a new matrix */
    glPushMatrix();

    /* Apply all transformation to model. Note that the transformations are applied starting
     * from the last one and ending with the first one */

    /* move model to its location */
    glTranslatef(screenPos[0]* viddef.rx, screenPos[1]* viddef.ry, 0);
    /* scale model to proper resolution */
    glScalef(viddef.rx, viddef.ry, 1.0f);
    /* rotate model to proper direction. */
    glRotatef(-90.f + direction, 0, 0, 1);

    R_DrawModelDirect(&mi, nullptr, nullptr);

    /* restore previous matrix */
    glPopMatrix();
}

void R_Draw3DMapMarkers (const vec2_t nodePos, const vec2_t nodeSize, const vec3_t rotate, const vec2_t pos, float direction, float earthRadius, const char* model, int skin)
{
    /* normalize */
    const float nx = nodePos[0] * viddef.rx;
    const float ny = nodePos[1] * viddef.ry;
    const float nw = nodeSize[0] * viddef.rx;
    const float nh = nodeSize[1] * viddef.ry;

    /* Earth center is in the middle of node.
     * Due to Orthographic view, this is also camera position */
    const vec3_t earthPos = {nx + nw / 2.0f, ny + nh / 2.0f, 0.0f};

    modelInfo_t mi;
    vec2_t size;
    vec3_t scale, center, position, angles;
    float zoom = 0.4f;

    OBJZERO(mi);
    VectorCopy(vec3_origin, position);
    VectorCopy(vec3_origin, angles);

    mi.model = R_FindModel(model);
    if (!mi.model) {
        Com_Printf("Could not find model '%s'\n", model);
        return;
    }

    mi.name = model;
    mi.origin = position;
    mi.angles = angles;
    mi.skin = skin;

    size[0] = size[1] = MARKER_SIZE * zoom;
    R_ModelAutoScale(size, &mi, scale, center);
    /* reset the center, as we want to place the models onto the surface of the earth */
    mi.center = nullptr;

    /* go to a new matrix */
    glPushMatrix();

    /* Apply all transformation to model. Note that the transformations are applied starting
     * from the last one and ending with the first one */

    /* center model on earth. Translate also along z to avoid seeing
     * bottom part of the model through earth (only half of earth is drawn) */
    glTranslatef(earthPos[0], earthPos[1], 10.0f);
    /* scale model to proper resolution */
    glScalef(viddef.rx, viddef.ry, 1.0f);
    /* place model on earth: make it tangent to earth surface, heading toward it if direction is used. */
    glRotatef(-rotate[1], 1, 0, 0);
    glRotatef(rotate[2], 0, 1, 0);
    glRotatef(rotate[0] - pos[0], 0, 0, 1);
    glRotatef(90.0f - pos[1], 1, 0, 0);
    glTranslatef(0, 0, earthRadius);
    glRotatef(90.0f + direction, 0, 0, 1);

    R_DrawModelDirect(&mi, nullptr, nullptr);

    /* restore previous matrix */
    glPopMatrix();
}

#define SKYBOX_HALFSIZE 800.0f

static const float starFieldVerts[] = {
    /* face 1 */
    -SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE,
    +SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE,
    +SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE,
    -SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE,

    /* face 2 */
    -SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE,
    +SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE,
    +SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE,
    -SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE,

    /* face 3 */
    +SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE,
    +SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE,
    +SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE,
    +SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE,

    /* face 4 */
    -SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE,
    -SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE,
    -SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE,
    -SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE,

    /* face 5 */
    -SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE,
    +SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE,
    +SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE,
    -SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE,

    /* face 6 */
    -SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE,
    +SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE, +SKYBOX_HALFSIZE,
    +SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE,
    -SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE, -SKYBOX_HALFSIZE
};

static const float starFieldTexCoords[] = {
    0.0, 0.0, 1.0, 0.0, 1.0, 1.0, 0.0, 1.0,
    0.0, 0.0, 1.0, 0.0, 1.0, 1.0, 0.0, 1.0,
    0.0, 0.0, 1.0, 0.0, 1.0, 1.0, 0.0, 1.0,
    0.0, 0.0, 1.0, 0.0, 1.0, 1.0, 0.0, 1.0,
    0.0, 0.0, 1.0, 0.0, 1.0, 1.0, 0.0, 1.0,
    0.0, 0.0, 1.0, 0.0, 1.0, 1.0, 0.0, 1.0,
};

static void R_DrawStarfield (int texnum, const vec3_t pos, const vec3_t rotate, float timeOfDay)
{
    vec3_t angle;       
    /* go to a new matrix */
    glPushMatrix();

    /* we must center the skybox on the camera border of view, and not on the earth, in order
     * to see only the inside of the cube */
    glTranslatef(pos[0], pos[1], -SKYBOX_DEPTH);

    /* rotates starfield: only time and rotation of earth around itself causes starfield to rotate. */
    VectorSet(angle, rotate[0] - timeOfDay * todeg, rotate[1], rotate[2]);
    glRotatef(angle[YAW], 1, 0, 0);
    glRotatef(angle[ROLL], 0, 1, 0);
    glRotatef(angle[PITCH], 0, 0, 1);

    R_BindTexture(texnum);

    /* alter the array pointers */
    glVertexPointer(3, GL_FLOAT, 0, starFieldVerts);
    glTexCoordPointer(2, GL_FLOAT, 0, starFieldTexCoords);

    /* draw the cube */
#ifdef GL_VERSION_ES_CM_1_0
    for( int ii = 0; ii < 6; ii++ )
        glDrawArrays(GL_TRIANGLE_FAN, ii * 4, 4);
#else
    glDrawArrays(GL_QUADS, 0, 24);
#endif

    refdef.batchCount++;

    /* restore previous matrix */
    glPopMatrix();
}

static inline void R_RotateCelestialBody (const vec4_t v, vec4_t r, const vec3_t rotate, const vec3_t earthPos, const float celestialDist)
{
    vec4_t v1;
    vec3_t v2;
    vec3_t rotationAxis;

    VectorSet(v2, v[1], v[0], v[2]);
    VectorSet(rotationAxis, 0, 0, 1);
    RotatePointAroundVector(v1, rotationAxis, v2, -rotate[PITCH]);
    VectorSet(rotationAxis, 0, 1, 0);
    RotatePointAroundVector(v2, rotationAxis, v1, -rotate[YAW]);

    Vector4Set(r, earthPos[0] + celestialDist * v2[1], earthPos[1] + celestialDist * v2[0], -celestialDist * v2[2], 0);
}

void R_Draw3DGlobe (const vec2_t pos, const vec2_t size, int day, int second, const vec3_t rotate, float zoom, const char* map,
                    bool disableSolarRender, float ambient, bool overlayNation, bool overlayXVI, bool overlayRadar, image_t* r_xviTexture,
                    image_t* r_radarTexture, bool renderNationGlow)
{
    /* globe scaling */
    const float fullscale = zoom / STANDARD_3D_ZOOM;

    /* lighting colors */
    static const vec4_t diffuseLightColor = { 1.75f, 1.75f, 1.75f, 1.0f };
    static const vec4_t specularLightColor = { 2.0f, 1.9f, 1.7f, 1.0f };
    static const vec4_t darknessLightColor = { 0.0f, 0.0f, 0.0f, 1.0f };
    static const vec4_t brightDiffuseLightColor = { 5.0f, 5.0f, 5.0f, 1.0f };
    const vec4_t ambientLightColor = { ambient + 0.2f, ambient + 0.2f, ambient + 0.2f, ambient + 0.2f };
    /* billboard textures */
    image_t* starfield;
    image_t* sun;
    image_t* sunOverlay;

    /* set distance of the sun and moon to make them static on starfield when
     * time is stoped.  this distance should be used for any celestial body
     * considered at infinite location (sun, moon) */
    static const float celestialDist = 1.37f * SKYBOX_HALFSIZE;
    static const float moonSize = 0.025f;
    vec4_t sunPos;
    vec4_t antiSunPos;
    vec4_t moonLoc;
    vec4_t sunLoc;

    /* normalize */
    const float nx = pos[0] * viddef.rx;
    const float ny = pos[1] * viddef.ry;
    const float nw = size[0] * viddef.rx;
    const float nh = size[1] * viddef.ry;

    /* Earth center is in the middle of node.
     * Due to Orthographic view, this is also camera position */
    const vec3_t earthPos = { nx + nw / 2.0f, ny + nh / 2.0f, 0.0f };

    /* estimate the progress through the current season so we can do
     * smooth transitions between textures.  Currently there are 12
     * "seasons", because we have one image per Earth-month. */
    const float season = (float) (day % DateTime::DAYS_PER_YEAR) / ((float) (DateTime::DAYS_PER_YEAR) / (float) (DateTime::SEASONS_PER_YEAR));
    const int currSeason = (int) floorf(season) % DateTime::SEASONS_PER_YEAR;
    const int nextSeason = (int) ceilf(season) % DateTime::SEASONS_PER_YEAR;
    const float seasonProgress = season - (float) currSeason;

    /* Compute sun position in absolute frame */
    const float q = (day % DateTime::DAYS_PER_YEAR * DateTime::SECONDS_PER_DAY + second) * (2.0f * M_PI / (DateTime::SECONDS_PER_DAY * DateTime::DAYS_PER_YEAR));   /* sun rotation (year) */
    const float a = cos(q) * SIN_ALPHA; /* due to earth obliquity */
    const float sqrta = sqrt(0.5f * (1 - a * a));

    /* earth rotation (day) */
    const float p = (second - DateTime::SECONDS_PER_DAY / 4) * (2.0f * M_PI / DateTime::SECONDS_PER_DAY);
    /* lunar orbit */
    const float m = p + (((double)((10 * day % 249) / 10.0f) + ((double)second / (double)DateTime::SECONDS_PER_DAY)) / 24.9f) * (2.0f * M_PI);

    glPushMatrix();
    glMatrixMode(GL_TEXTURE);
    glLoadIdentity();
    glMatrixMode(GL_MODELVIEW);
    glDisable(GL_LIGHTING);
    /* draw the starfield, rotating with the planet */
    starfield = R_FindImage(va("pics/geoscape/%s_stars", map), it_wrappic);
    if (starfield != r_noTexture)
        R_DrawStarfield(starfield->texnum, earthPos, rotate, p);

    glPopMatrix();

    /* set up position vectors for celestial bodies */
    Vector4Set(sunPos, cos(p) * sqrta, -sin(p) * sqrta, a, 0);
    Vector4Set(antiSunPos, -cos(p) * sqrta, sin(p) * sqrta, -a, 0);

    /* Rotate the sun in the relative frame of player view, to get sun location */
    R_RotateCelestialBody(sunPos, sunLoc, rotate, earthPos, 1.0f);
    /* load sun texture image */
    sun = R_FindImage(va("pics/geoscape/%s_sun", map), it_wrappic);
    sunOverlay = R_FindImage(va("pics/geoscape/%s_sun_overlay", map), it_pic);
    if (sun != r_noTexture && sunOverlay != r_noTexture && sunLoc[2] > 0 && !disableSolarRender) {
        const int sunx = earthPos[0] + viddef.rx * (-128.0f + celestialDist * (sunLoc[0] - earthPos[0]));
        const int suny = earthPos[1] + viddef.ry * (-128.0f + celestialDist * (sunLoc[1] - earthPos[1]));

        R_DrawTexture(sunOverlay->texnum, sunx, suny, 256.0f * viddef.rx, 256.0f * viddef.ry);
        R_DrawBuffers(2);
        R_DrawTexture(sun->texnum, sunx, suny, 256.0 * viddef.rx, 256.0 * viddef.ry);
        R_DrawBuffers(1);
    }

    /* calculate position of the moon (it rotates around earth with a period of
     * about 24.9 h, and we must take day into account to avoid moon to "jump"
     * every time the day is changing) */
    VectorSet(moonLoc, cos(m) * sqrta, -sin(m) * sqrta, a);
    R_RotateCelestialBody(moonLoc, moonLoc, rotate, earthPos, celestialDist);

    /* free last month's texture image */
    if (r_globeEarth.season != currSeason) {
        r_globeEarth.season = currSeason;
        R_FreeImage(r_globeEarth.texture);
    }

    /* load diffuse texture map (with embedded night-glow map as alpha channel) */
    r_globeEarth.texture = R_FindImage(va("pics/geoscape/%s/%s_season_%02d", r_config.lodDir, map, currSeason), it_wrappic);
    if (r_globeEarth.texture == r_noTexture)
        Com_Error(ERR_FATAL, "Could not find pics/geoscape/%s/%s_season_%02d\n", r_config.lodDir, map, currSeason);

    /* set up for advanced GLSL rendering if we have the capability */
    if (r_programs->integer) {
        r_globeEarth.glslProgram = r_state.geoscape_program;
        /* load earth image for the next month so we can blend them */
        r_globeEarth.blendTexture = R_FindImage(va("pics/geoscape/%s/%s_season_%02d", r_config.lodDir, map, nextSeason), it_wrappic);
        if (r_globeEarth.blendTexture == r_noTexture)
            Com_Error(ERR_FATAL, "Could not find pics/geoscape/%s/%s_season_%02d\n", r_config.lodDir, map, nextSeason);

        /* load normal map (with embedded gloss map as alpha channel) */
        r_globeEarth.normalMap = R_FindImage(va("pics/geoscape/%s/%s_bump", r_config.lodDir, map), it_wrappic);
        if (r_globeEarth.normalMap == r_noTexture)
            r_globeEarth.normalMap = nullptr;

        /* weight the blending based on how much of the month has elapsed */
        r_globeEarth.blendScale = seasonProgress;
        /* set up lights for nighttime city glow */
        VectorCopy(antiSunPos, r_globeEarth.nightLightPos);
        glLightfv(GL_LIGHT1, GL_AMBIENT, darknessLightColor);
        glLightfv(GL_LIGHT1, GL_DIFFUSE, brightDiffuseLightColor);
        glLightfv(GL_LIGHT1, GL_SPECULAR, darknessLightColor);

        r_globeEarth.glowScale = 0.7f;
    }

    /* load moon texture image */
    r_globeMoon.texture = R_FindImage(va("pics/geoscape/%s_moon", map), it_wrappic);

    /* globe texture scaling */
    glMatrixMode(GL_TEXTURE);
    glLoadIdentity();
    glScalef(2.0f, 1.0f, 1.0f);
    glMatrixMode(GL_MODELVIEW);

    /* enable the lighting */
    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);
    glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuseLightColor);
    glLightfv(GL_LIGHT0, GL_AMBIENT, ambientLightColor);
    glLightfv(GL_LIGHT0, GL_SPECULAR, specularLightColor);

    /* draw the moon */
    if (r_globeMoon.texture != r_noTexture && moonLoc[2] > 0 && !disableSolarRender)
        R_SphereRender(&r_globeMoon, moonLoc, rotate, moonSize, sunPos);

    /* activate depth to hide 3D models behind earth */
    glEnable(GL_DEPTH_TEST);

    /* draw the earth */
    R_DrawBuffers(2);
#if 0 /* old rendering code which doesn't render city lights in FFP */
    if (r_programs->integer == 0) /* ignore alpha channel, since the city-light map is stored there */
        glBlendFunc(GL_ONE, GL_ZERO);

    R_SphereRender(&r_globeEarth, earthPos, rotate, fullscale, sunPos);

    if (r_programs->integer == 0) /* restore default blend function */
        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
#else /* new which does render city lights in FFP */
    if (r_programs->integer == 0) {
        /* set up rendering of city lights map, which is stored in alpha channel; OpenGL 1.3 required */
        R_SelectTexture(&texunit_diffuse); /* select texture to edit texture environment for */
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE); /* enable color combiner */
        /* setup texture combiner to blend between daylight diffuse map stored in the RGB channels of the diffuse texture
         * and the monochomatic emission map (which simulates city lights) stored in the alpha channel;
         * incoming color value is the blend factor.
         */
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_TEXTURE); /* set day color as blending target*/
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, GL_SRC_COLOR);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_TEXTURE); /* set night color as blending source */
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_RGB, GL_SRC_ALPHA);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE2_RGB, GL_PREVIOUS); /* set incoming color as blending factor */
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND2_RGB, GL_SRC_COLOR);
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_INTERPOLATE); /* set blending mode to interpolation from src1 to src0 */
        /* copy alpha from incoming color, bypassing the value read from texture, which is not a "real" alpha anyway */
        glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_REPLACE);
        glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_ALPHA, GL_PREVIOUS);
        glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_ALPHA, GL_SRC_ALPHA);
    }

    R_SphereRender(&r_globeEarth, earthPos, rotate, fullscale, sunPos);

    if (r_programs->integer == 0) { /* disable combiner */
        R_SelectTexture(&texunit_diffuse);
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
    }
#endif

    r_globeEarthAtmosphere.texture = R_FindImage(va("pics/geoscape/%s_atmosphere", map), it_wrappic);

    /* Draw earth atmosphere */
    if (r_programs->integer && r_postprocess->integer) {
        r_globeEarthAtmosphere.normalMap = r_globeEarth.normalMap;
        r_globeEarthAtmosphere.glowScale = 1.0;
        r_globeEarthAtmosphere.blendScale = -1.0;
        r_globeEarthAtmosphere.glslProgram = r_state.atmosphere_program;
        R_SphereRender(&r_globeEarthAtmosphere, earthPos, rotate, fullscale, sunPos);
    } else {
        image_t* halo = R_FindImage("pics/geoscape/map_earth_halo", it_pic);
        if (halo != r_noTexture) {
            const float earthSizeX = fullscale * 20500.0f * viddef.rx;
            const float earthSizeY = fullscale * 20500.0f * viddef.ry;
            glMatrixMode(GL_TEXTURE);
            glPushMatrix();
            glLoadIdentity();
            glDisable(GL_LIGHTING);

            R_DrawTexture(halo->texnum, earthPos[0] - earthSizeX * 0.5f, earthPos[1] - earthSizeY * 0.5f, earthSizeX, earthSizeY);
            glEnable(GL_LIGHTING);
            glPopMatrix();
            glMatrixMode(GL_MODELVIEW);
        }
    }

    R_DrawBuffers(1);
    glDisable(GL_DEPTH_TEST);

    /* draw nation overlay */
    if (overlayNation) {
        r_globeEarth.overlay = R_FindImage(va("pics/geoscape/%s_nations_overlay", map), it_wrappic);
        if (r_globeEarth.overlay == r_noTexture)
            Com_Error(ERR_FATAL, "Could not load geoscape nation overlay image");

        R_SphereRender(&r_globeEarth, earthPos, rotate, fullscale, sunPos);

        if (renderNationGlow) {
            /* draw glowing borders */
            r_globeEarth.overlay = R_FindImage(va("pics/geoscape/%s_nations_overlay_glow", map), it_wrappic);
            if (r_globeEarth.overlay == r_noTexture)
                Com_Error(ERR_FATAL, "Could not load geoscape nation overlay glow image");

            R_DrawBuffers(2);
            glDisable(GL_LIGHTING);
            R_SphereRender(&r_globeEarth, earthPos, rotate, fullscale, sunPos);
            glEnable(GL_LIGHTING);
            R_DrawBuffers(1);
        }

        r_globeEarth.overlay = nullptr;
    }
    /* draw XVI overlay */
    if (overlayXVI) {
        r_globeEarth.overlay = R_FindImage(va("pics/geoscape/%s_xvi_overlay", map), it_wrappic);
        r_globeEarth.overlayAlphaMask = r_xviTexture;
        assert(r_globeEarth.overlayAlphaMask);
        R_SphereRender(&r_globeEarth, earthPos, rotate, fullscale, sunPos);
        r_globeEarth.overlayAlphaMask = nullptr;
        r_globeEarth.overlay = nullptr;
    }
    /* draw radar overlay */
    if (overlayRadar) {
        r_globeEarth.overlay = r_radarTexture;
        assert(r_globeEarth.overlay);
        R_SphereRender(&r_globeEarth, earthPos, rotate, fullscale, sunPos);
        r_globeEarth.overlay = nullptr;
    }

    /* disable 3d geoscape lighting */
    glDisable(GL_LIGHTING);

    /* restore the previous matrix */
    glMatrixMode(GL_TEXTURE);
    glLoadIdentity();
    glMatrixMode(GL_MODELVIEW);
}

static inline void R_DrawQuad (void)
{
    const vec2_t texcoord[] = { { 0.0f, 1.0f }, { 1.0f, 1.0f }, { 1.0f, 0.0f }, { 0.0f, 0.0f } };
    const vec2_t verts[] = { { 0.0f, 0.0f }, Vector2FromInt(fbo_render->width, 0.0f), Vector2FromInt(fbo_render->width, fbo_render->height), Vector2FromInt(0.0f, fbo_render->height) };

    glVertexPointer(2, GL_FLOAT, 0, verts);
    R_BindArray(GL_TEXTURE_COORD_ARRAY, GL_FLOAT, texcoord);

    glDrawArrays(GL_TRIANGLE_FAN, 0, 4);

    refdef.batchCount++;

    R_BindDefaultArray(GL_TEXTURE_COORD_ARRAY);
    R_BindDefaultArray(GL_VERTEX_ARRAY);
}

static void R_Blur (r_framebuffer_t* source, r_framebuffer_t* dest, int tex, int dir)
{
    R_EnableBlur(r_state.convolve_program, true, source, dest, dir);

    /* draw new texture onto a flat surface */
    R_BindTextureForTexUnit(source->textures[tex], &texunit_0);
    R_UseViewport(source);
    R_DrawQuad();

    R_EnableBlur(r_state.convolve_program, false, nullptr, nullptr, 0);
}

static void R_BlurStack (int levels, r_framebuffer_t** sources, r_framebuffer_t** dests)
{
    for (int i = 0; i < levels; i++) {
        const int l = levels - i - 1;

        R_UseProgram(i == 0 ? default_program : r_state.combine2_program);
        R_UseFramebuffer(dests[l]);
        R_BindTextureForTexUnit(sources[l]->textures[0], &texunit_0);
        if (i != 0)
            R_BindTextureForTexUnit(dests[l + 1]->textures[0], &texunit_1);

        R_UseViewport(sources[l]);
        R_DrawQuad();

        R_Blur(dests[l], sources[l], 0, 1);
        R_Blur(sources[l], dests[l], 0, 0);
    }
}

void R_DrawBloom (void)
{
    int i;
    bool renderBufferState;

    if (!r_config.frameBufferObject || !r_postprocess->integer || !r_programs->integer)
        return;

    /* save state, then set up for blit-style rendering to quads */
    renderBufferState = R_RenderbufferEnabled();
    glMatrixMode(GL_MODELVIEW);
    glPushMatrix();
    glLoadIdentity();
    glMatrixMode(GL_TEXTURE);
    glPushMatrix();
    glLoadIdentity();
    glMatrixMode(GL_PROJECTION);
    glPushMatrix();
    glLoadIdentity();
#ifndef GL_VERSION_ES_CM_1_0
    glPushAttrib(GL_ENABLE_BIT | GL_VIEWPORT_BIT | GL_LIGHTING_BIT | GL_DEPTH_BUFFER_BIT);
#endif
    glOrtho(0, viddef.context.width, viddef.context.height, 0, 9999.0f, SKYBOX_DEPTH);

    glDisable(GL_LIGHTING);
    glDisable(GL_DEPTH_TEST);

    /* downsample into image pyramid */
    R_ResolveMSAA(fbo_render);
    R_BindTexture(fbo_render->textures[1]);
    qglGenerateMipmapEXT(GL_TEXTURE_2D);

    R_Blur(fbo_render, fbo_bloom0, 1, 0);
    R_Blur(fbo_bloom0, fbo_bloom1, 0, 1);

    R_UseFramebuffer(r_state.buffers0[0]);
    R_BindTexture(fbo_bloom1->textures[0]);
    qglGenerateMipmapEXT(GL_TEXTURE_2D);
    R_UseViewport(r_state.buffers0[0]);
    R_DrawQuad();

    for (i = 1; i < DOWNSAMPLE_PASSES; i++) {
        R_Blur(r_state.buffers0[i - 1], r_state.buffers1[i - 1], 0, 0);
        R_Blur(r_state.buffers1[i - 1], r_state.buffers2[i - 1], 0, 1);
        R_UseFramebuffer(r_state.buffers0[i]);
        R_BindTexture(r_state.buffers2[i - 1]->textures[0]);
        R_UseViewport(r_state.buffers0[i]);
        R_DrawQuad();
    }

    /* blur and combine downsampled images */
    R_BlurStack(DOWNSAMPLE_PASSES, r_state.buffers0, r_state.buffers1);

    /* re-combine the blurred version with the original "glow" image */
    R_UseProgram(r_state.combine2_program);
    R_UseFramebuffer(fbo_bloom0);
    R_BindTextureForTexUnit(fbo_render->textures[1], &texunit_0);
    R_BindTextureForTexUnit(r_state.buffers1[0]->textures[0], &texunit_1);

    R_UseViewport(fbo_screen);
    R_DrawQuad();

    /* draw final result to the screenbuffer */
    R_UseFramebuffer(fbo_screen);
    R_UseProgram(r_state.combine2_program);
    R_BindTextureForTexUnit(fbo_render->textures[0], &texunit_0);
    R_BindTextureForTexUnit(fbo_bloom0->textures[0], &texunit_1);

    R_DrawQuad();

    /* cleanup before returning */
    R_UseProgram(default_program);

    R_CheckError();

#ifndef GL_VERSION_ES_CM_1_0
    glPopAttrib();
#endif
    glMatrixMode(GL_PROJECTION);
    glPopMatrix();
    glMatrixMode(GL_TEXTURE);
    glPopMatrix();
    glMatrixMode(GL_MODELVIEW);
    glPopMatrix();
    R_CheckError();

    /* reset renderbuffer state to what it was before */
    R_EnableRenderbuffer(renderBufferState);
}