psychedelia
int width int height int frames

static float prev[4][3], next[4][3];
static int   frame;
static float tweaks[3] = {33, 35, 37};
crimp_image* result;
int          yi, xi, c;
float        t, y, x;

result = crimp_new_rgba (width, height);

if (frame % frames == 0) {
    int i, c;
    if (frame == 0) {
        for (i = 0; i < 4; ++i) {
            for (c = 0; c < 3; ++c) {
                next[i][c] = rand() / (float)RAND_MAX;
            }
        }
    }
    for (i = 0; i < 4; ++i) {
        for (c = 0; c < 3; ++c) {
            prev[i][c] = next[i][c];
            next[i][c] = rand() / (float)RAND_MAX;
        }
    }
}

t = (cosf((frame % frames) / (float)frames * M_PI) + 1) / 2;
for (yi = 0, y = 0; yi < height; ++yi, y += 1. / height) {
    for (xi = 0, x = 0; xi < width; ++xi, x += 1. / width) {
        float i, v[3];
        for (c = 0; c < 3; ++c) {
            v[c] = cosf(frame / tweaks[c] + (
                (prev[0][c] * t + next[0][c] * (1 - t)) * (1 - y) * (1 - x)
              + (prev[1][c] * t + next[1][c] * (1 - t)) * (1 - y) * (    x)
              + (prev[2][c] * t + next[2][c] * (1 - t)) * (    y) * (1 - x)
              + (prev[3][c] * t + next[3][c] * (1 - t)) * (    y) * (    x)
            ) * 7 * M_PI);
        }
        i = (cosf((v[0] + v[1] + v[2] + frame / 17.) * M_PI) + 1) / 2;

	R (result, xi, yi) = CLAMP(0, v[0] * i * 255, 255);
	G (result, xi, yi) = CLAMP(0, v[1] * i * 255, 255);
	B (result, xi, yi) = CLAMP(0, v[2] * i * 255, 255);
	A (result, xi, yi) = OPAQUE;
    }
}

frame ++;

Tcl_SetObjResult(interp, crimp_new_image_obj (result));
return TCL_OK;

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