GameBoy\Core::drawSpritesForLine PHP Method

    public function drawSpritesForLine($line)
    {
        if (!$this->gfxSpriteShow) {
            return;
        }
        $minSpriteY = $line - ($this->gfxSpriteDouble ? 15 : 7);
        // either only do priorityFlag == 0 (all foreground),
        // or first 0x80 (background) and then 0 (foreground)
        $priorityFlag = $this->spritePriorityEnabled ? 0x80 : 0;
        for (; $priorityFlag >= 0; $priorityFlag -= 0x80) {
            $oamIx = 159;
            while ($oamIx >= 0) {
                $attributes = 0xff & $this->memory[0xfe00 + $oamIx--];
                if (($attributes & 0x80) == $priorityFlag || !$this->spritePriorityEnabled) {
                    $tileNum = 0xff & $this->memory[0xfe00 + $oamIx--];
                    $spriteX = (0xff & $this->memory[0xfe00 + $oamIx--]) - 8;
                    $spriteY = (0xff & $this->memory[0xfe00 + $oamIx--]) - 16;
                    $offset = $line - $spriteY;
                    if ($spriteX >= 160 || $spriteY < $minSpriteY || $offset < 0) {
                        continue;
                    }
                    if ($this->gfxSpriteDouble) {
                        $tileNum = $tileNum & 0xfe;
                    }
                    $spriteAttrib = $attributes >> 5 & 0x3;
                    // flipx: from bit 0x20 to 0x01, flipy: from bit 0x40 to 0x02
                    if ($this->cGBC) {
                        $spriteAttrib += 0x20 + (($attributes & 0x7) << 2);
                        // palette
                        $tileNum += (384 >> 3) * ($attributes & 0x8);
                        // tile vram bank
                    } else {
                        // attributes 0x10: 0x00 = OBJ1 palette, 0x10 = OBJ2 palette
                        // spriteAttrib: 0x04: OBJ1 palette, 0x08: OBJ2 palette
                        $spriteAttrib += 0x4 + (($attributes & 0x10) >> 2);
                    }
                    if ($priorityFlag == 0x80) {
                        // background
                        if ($this->gfxSpriteDouble) {
                            if (($spriteAttrib & 2) != 0) {
                                $this->drawPartBgSprite(($tileNum | 1) - ($offset >> 3), $spriteX, $line, $offset & 7, $spriteAttrib);
                            } else {
                                $this->drawPartBgSprite(($tileNum & -2) + ($offset >> 3), $spriteX, $line, $offset & 7, $spriteAttrib);
                            }
                        } else {
                            $this->drawPartBgSprite($tileNum, $spriteX, $line, $offset, $spriteAttrib);
                        }
                    } else {
                        // foreground
                        if ($this->gfxSpriteDouble) {
                            if (($spriteAttrib & 2) != 0) {
                                $this->drawPartFgSprite(($tileNum | 1) - ($offset >> 3), $spriteX, $line, $offset & 7, $spriteAttrib);
                            } else {
                                $this->drawPartFgSprite(($tileNum & -2) + ($offset >> 3), $spriteX, $line, $offset & 7, $spriteAttrib);
                            }
                        } else {
                            $this->drawPartFgSprite($tileNum, $spriteX, $line, $offset, $spriteAttrib);
                        }
                    }
                } else {
                    $oamIx -= 3;
                }
            }
        }
    }