r_corona.cpp

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/*
 * Copyright(c) 1997-2001 Id Software, Inc.
 * Copyright(c) 2002 The Quakeforge Project.
 * Copyright(c) 2006 Quake2World.
 *
 * 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"

void R_AddCorona (const vec3_t org, float radius, const vec3_t color)
{
    corona_t* c;

    if (!r_coronas->integer)
        return;

    if (refdef.numCoronas == MAX_CORONAS)
        return;

    c = &refdef.coronas[refdef.numCoronas++];

    VectorCopy(org, c->org);
    c->radius = radius;
    VectorCopy(color, c->color);
}

void R_DrawCoronas (void)
{
    if (!r_coronas->integer)
        return;

    if (!refdef.numCoronas)
        return;

    R_EnableTexture(&texunit_diffuse, false);

    R_EnableColorArray(true);

    R_ResetArrayState();

    R_BlendFunc(GL_ONE, GL_ONE);

    for (int k = 0; k < refdef.numCoronas; k++) {
        const corona_t* c = &refdef.coronas[k];
        int verts, vertind;

        if (!c->radius)
            continue;

        /* use at least 12 verts, more for larger coronas */
        verts = 12 + c->radius / 8;

        memcpy(&r_state.color_array[0], c->color, sizeof(vec3_t));
        r_state.color_array[3] = 1.0f; /* set origin color */

        /* and the corner colors */
        memset(&r_state.color_array[4], 0, verts * 2 * sizeof(vec4_t));

        memcpy(&r_state.vertex_array_3d[0], c->org, sizeof(vec3_t));
        vertind = 3; /* and the origin */

        for (int i = verts; i >= 0; i--) { /* now draw the corners */
            const float a = (M_PI * 2 / verts) * i;
            vec3_t v;

            for (int j = 0; j < 3; j++)
                v[j] = c->org[j] + r_locals.right[j] * (float) cos(a) * c->radius + r_locals.up[j] * (float) sin(a)
                        * c->radius;

            memcpy(&r_state.vertex_array_3d[vertind], v, sizeof(vec3_t));
            vertind += 3;
        }

        glDrawArrays(GL_TRIANGLE_FAN, 0, vertind / 3);

        refdef.batchCount++;
    }

    R_BlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

    R_EnableColorArray(false);

    R_EnableTexture(&texunit_diffuse, true);

    R_Color(nullptr);
}