r_lightning.c

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#include "quakedef.h"
#include "image.h"
 
cvar_t r_lightningbeam_thickness = {CF_CLIENT | CF_ARCHIVE, "r_lightningbeam_thickness", "8", "thickness of the lightning beam effect"};
cvar_t r_lightningbeam_scroll = {CF_CLIENT | CF_ARCHIVE, "r_lightningbeam_scroll", "5", "speed of texture scrolling on the lightning beam effect"};
cvar_t r_lightningbeam_repeatdistance = {CF_CLIENT | CF_ARCHIVE, "r_lightningbeam_repeatdistance", "128", "how far to stretch the texture along the lightning beam effect"};
cvar_t r_lightningbeam_color_red = {CF_CLIENT | CF_ARCHIVE, "r_lightningbeam_color_red", "1", "color of the lightning beam effect"};
cvar_t r_lightningbeam_color_green = {CF_CLIENT | CF_ARCHIVE, "r_lightningbeam_color_green", "1", "color of the lightning beam effect"};
cvar_t r_lightningbeam_color_blue = {CF_CLIENT | CF_ARCHIVE, "r_lightningbeam_color_blue", "1", "color of the lightning beam effect"};
cvar_t r_lightningbeam_qmbtexture = {CF_CLIENT | CF_ARCHIVE, "r_lightningbeam_qmbtexture", "0", "load the qmb textures/particles/lightning.pcx texture instead of generating one, can look better"};
 
static texture_t cl_beams_externaltexture;
static texture_t cl_beams_builtintexture;
 
static void r_lightningbeams_start(void)
{
    memset(&cl_beams_externaltexture, 0, sizeof(cl_beams_externaltexture));
    memset(&cl_beams_builtintexture, 0, sizeof(cl_beams_builtintexture));
}
 
static void CL_Beams_SetupExternalTexture(void)
{
    if (Mod_LoadTextureFromQ3Shader(r_main_mempool, "r_lightning.c", &cl_beams_externaltexture, "textures/particles/lightning", false, false, TEXF_ALPHA | TEXF_FORCELINEAR, MATERIALFLAG_WALL | MATERIALFLAG_NOCULLFACE | MATERIALFLAG_VERTEXCOLOR | MATERIALFLAG_ALPHAGEN_VERTEX | MATERIALFLAG_ADD | MATERIALFLAG_BLENDED | MATERIALFLAG_NOSHADOW))
        Cvar_SetValueQuick(&r_lightningbeam_qmbtexture, false);
}
 
static void CL_Beams_SetupBuiltinTexture(void)
{
    // beam direction is horizontal in the lightning texture
    int texwidth = 128;
    int texheight = 64;
    float r, g, b, intensity, thickness = texheight * 0.25f, border = thickness + 2.0f, ithickness = 1.0f / thickness, center, n;
    int x, y;
    unsigned char *data;
    skinframe_t *skinframe;
    float centersamples[17][2];
 
    // make a repeating noise pattern for the beam path
    for (x = 0; x < 16; x++)
    {
        centersamples[x][0] = lhrandom(border, texheight - border);
        centersamples[x][1] = lhrandom(0.2f, 1.00f);
    }
    centersamples[16][0] = centersamples[0][0];
    centersamples[16][1] = centersamples[0][1];
 
    data = (unsigned char *)Mem_Alloc(tempmempool, texwidth * texheight * 4);
 
    // iterate by columns and draw the entire column of pixels
    for (x = 0; x < texwidth; x++)
    {
        r = x * 16.0f / texwidth;
        y = (int)r;
        g = r - y;
        center = centersamples[y][0] * (1.0f - g) + centersamples[y+1][0] * g;
        n = centersamples[y][1] * (1.0f - g) + centersamples[y + 1][1] * g;
        for (y = 0; y < texheight; y++)
        {
            intensity = 1.0f - fabs((y - center) * ithickness);
            if (intensity > 0)
            {
                intensity = pow(intensity * n, 2);
                r = intensity * 1.000f * 255.0f;
                g = intensity * 2.000f * 255.0f;
                b = intensity * 4.000f * 255.0f;
                data[(y * texwidth + x) * 4 + 2] = (unsigned char)(bound(0, r, 255));
                data[(y * texwidth + x) * 4 + 1] = (unsigned char)(bound(0, g, 255));
                data[(y * texwidth + x) * 4 + 0] = (unsigned char)(bound(0, b, 255));
            }
            else
                intensity = 0.0f;
            data[(y * texwidth + x) * 4 + 3] = (unsigned char)255;
        }
    }
 
    skinframe = R_SkinFrame_LoadInternalBGRA("lightningbeam", TEXF_FORCELINEAR, data, texwidth, texheight, 0, 0, 0, false);
    Mod_LoadCustomMaterial(r_main_mempool, &cl_beams_builtintexture, "cl_beams_builtintexture", 0, MATERIALFLAG_WALL | MATERIALFLAG_NOCULLFACE | MATERIALFLAG_VERTEXCOLOR | MATERIALFLAG_ALPHAGEN_VERTEX | MATERIALFLAG_ADD | MATERIALFLAG_BLENDED | MATERIALFLAG_NOSHADOW, skinframe);
    Mem_Free(data);
}
 
static void r_lightningbeams_shutdown(void)
{
    memset(&cl_beams_externaltexture, 0, sizeof(cl_beams_externaltexture));
    memset(&cl_beams_builtintexture, 0, sizeof(cl_beams_builtintexture));
}
 
static void r_lightningbeams_newmap(void)
{
    if (cl_beams_externaltexture.currentskinframe)
        R_SkinFrame_MarkUsed(cl_beams_externaltexture.currentskinframe);
    if (cl_beams_builtintexture.currentskinframe)
        R_SkinFrame_MarkUsed(cl_beams_builtintexture.currentskinframe);
}
 
void R_LightningBeams_Init(void)
{
    Cvar_RegisterVariable(&r_lightningbeam_thickness);
    Cvar_RegisterVariable(&r_lightningbeam_scroll);
    Cvar_RegisterVariable(&r_lightningbeam_repeatdistance);
    Cvar_RegisterVariable(&r_lightningbeam_color_red);
    Cvar_RegisterVariable(&r_lightningbeam_color_green);
    Cvar_RegisterVariable(&r_lightningbeam_color_blue);
    Cvar_RegisterVariable(&r_lightningbeam_qmbtexture);
    R_RegisterModule("R_LightningBeams", r_lightningbeams_start, r_lightningbeams_shutdown, r_lightningbeams_newmap, NULL, NULL);
}
 
static void CL_Beam_AddQuad(model_t *mod, msurface_t *surf, const vec3_t start, const vec3_t end, const vec3_t offset, float t1, float t2)
{
    int e0, e1, e2, e3;
    vec3_t n;
    vec3_t dir;
    float c[4];
 
    Vector4Set(c, r_lightningbeam_color_red.value, r_lightningbeam_color_green.value, r_lightningbeam_color_blue.value, 1.0f);
 
    VectorSubtract(end, start, dir);
    CrossProduct(dir, offset, n);
    VectorNormalize(n);
 
    e0 = Mod_Mesh_IndexForVertex(mod, surf, start[0] + offset[0], start[1] + offset[1], start[2] + offset[2], n[0], n[1], n[2], t1, 0, 0, 0, c[0], c[1], c[2], c[3]);
    e1 = Mod_Mesh_IndexForVertex(mod, surf, start[0] - offset[0], start[1] - offset[1], start[2] - offset[2], n[0], n[1], n[2], t1, 1, 0, 0, c[0], c[1], c[2], c[3]);
    e2 = Mod_Mesh_IndexForVertex(mod, surf, end[0] - offset[0], end[1] - offset[1], end[2] - offset[2], n[0], n[1], n[2], t2, 1, 0, 0, c[0], c[1], c[2], c[3]);
    e3 = Mod_Mesh_IndexForVertex(mod, surf, end[0] + offset[0], end[1] + offset[1], end[2] + offset[2], n[0], n[1], n[2], t2, 0, 0, 0, c[0], c[1], c[2], c[3]);
    Mod_Mesh_AddTriangle(mod, surf, e0, e1, e2);
    Mod_Mesh_AddTriangle(mod, surf, e0, e2, e3);
}
 
void CL_Beam_AddPolygons(const beam_t *b)
{
    vec3_t beamdir, right, up, offset, start, end;
    vec_t beamscroll = r_refdef.scene.time * -r_lightningbeam_scroll.value;
    vec_t beamrepeatscale = 1.0f / r_lightningbeam_repeatdistance.value;
    float length, t1, t2;
    model_t *mod;
    msurface_t *surf;
 
    if (r_lightningbeam_qmbtexture.integer && cl_beams_externaltexture.currentskinframe == NULL)
        CL_Beams_SetupExternalTexture();
    if (!r_lightningbeam_qmbtexture.integer && cl_beams_builtintexture.currentskinframe == NULL)
        CL_Beams_SetupBuiltinTexture();
 
    // calculate beam direction (beamdir) vector and beam length
    // get difference vector
    CL_Beam_CalculatePositions(b, start, end);
    VectorSubtract(end, start, beamdir);
    // find length of difference vector
    length = sqrt(DotProduct(beamdir, beamdir));
    // calculate scale to make beamdir a unit vector (normalized)
    t1 = 1.0f / length;
    // scale beamdir so it is now normalized
    VectorScale(beamdir, t1, beamdir);
 
    // calculate up vector such that it points toward viewer, and rotates around the beamdir
    // get direction from start of beam to viewer
    VectorSubtract(r_refdef.view.origin, start, up);
    // remove the portion of the vector that moves along the beam
    // (this leaves only a vector pointing directly away from the beam)
    t1 = -DotProduct(up, beamdir);
    VectorMA(up, t1, beamdir, up);
    // generate right vector from forward and up, the result is unnormalized
    CrossProduct(beamdir, up, right);
    // now normalize the right vector and up vector
    VectorNormalize(right);
    VectorNormalize(up);
 
    // calculate T coordinate scrolling (start and end texcoord along the beam)
    t1 = beamscroll;
    t1 = t1 - (int)t1;
    t2 = t1 + beamrepeatscale * length;
 
    // the beam is 3 polygons in this configuration:
    //  *   2
    //   * *
    // 1*****
    //   * *
    //  *   3
    // they are showing different portions of the beam texture, creating an
    // illusion of a beam that appears to curl around in 3D space
    // (and realize that the whole polygon assembly orients itself to face
    //  the viewer)
 
    mod = CL_Mesh_Scene();
    surf = Mod_Mesh_AddSurface(mod, r_lightningbeam_qmbtexture.integer ? &cl_beams_externaltexture : &cl_beams_builtintexture, false);
    // polygon 1
    VectorM(r_lightningbeam_thickness.value, right, offset);
    CL_Beam_AddQuad(mod, surf, start, end, offset, t1, t2);
    // polygon 2
    VectorMAM(r_lightningbeam_thickness.value * 0.70710681f, right, r_lightningbeam_thickness.value * 0.70710681f, up, offset);
    CL_Beam_AddQuad(mod, surf, start, end, offset, t1 + 0.33f, t2 + 0.33f);
    // polygon 3
    VectorMAM(r_lightningbeam_thickness.value * 0.70710681f, right, r_lightningbeam_thickness.value * -0.70710681f, up, offset);
    CL_Beam_AddQuad(mod, surf, start, end, offset, t1 + 0.66f, t2 + 0.66f);
}